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  • Articles  (140)
  • geochemistry  (74)
  • Rhizosphere  (66)
  • Springer  (140)
  • Geosciences  (140)
  • 1
    Electronic Resource
    Electronic Resource
    Scandian ixiolite, pyrochlore and bazzite in granite pegmatite in terdal, Telemark, Norway. A contribution to the mineralogy and geochemistry of scandium and tin (1988)
    Springer
    Mineralogy and petrology 38 (1988), S. 229-243 
    Details
    ISSN: 1438-1168
    Keywords: Scandium ; tin ; beryllium ; mineralogy ; geochemistry ; pegmatite ; Scandium ; Zinn ; Beryllium ; Mineralogie ; Geochemie ; Pegmatit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung In Tørdal durchschneiden Granit-pegmatitische Gänge eine vulkano-sedimentäre Abfolge, die über einem älteren Gneis-Basement und einem jüngeren Granit, von dem die Gänge stammen, liegt. Positive Kovariation von Scandium, Lithium, Beryllium und Zinn, die sich im Zuge eines Prospektionsprogrammes auf Zinn ergaben, deuten auf eine mögliche Anreicherung von Scandium und Zinn während des Aufstieges pegmatitischer Phasen durch die vulkano-sedimentäre Abfolge hin. Ein Scandium-reicher Ixiolit in Assoziation mit Pyrochlor und Bazzit wird beschrieben, der aus einem Clea-velandit-Amazonit-Pegmatit stammt. Der Pegmatit bildet einen Teil eines größeren Netzwerkes von granit-pegmatischen Gängen. Eine Alteration von Ixiolit zu Pyrochlor tritt als spätmagmatisch-hydrothermales Ereignis auf.
    Notes: Summary In Tørdal granite pegmatite veins cut through a volcano-sedimentary sequence which overlies an older, gneissic basement and younger granite from which they originate. Positive co-variations of scandium, lithium, beryllium and tin, which were documented through a recent prospecting program for tin, indicate a possible enrichment of scandium and tin during the passage of the pegmatitic material through the volcanic sedimentary sequence. A description is given of scandium-rich ixiolite, (Ta,Nb,Sc,Sn,Fe,Mn,Ti)2O4 in association with pyrochlore, (Ca,Sc,Y,Sn,U)2(Ta,Nb,Ti)2O6(O,OH,F) and bazzite, Be3Sc2Si6O18 from a cleavelandite-amazonite pegmatite occurring as a part of a larger network of granitic pegmatite veins. Alteration from ixiolite to pyrochlore appears as a late magmatic-hydrothermal event.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01167090
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  • 2
    Electronic Resource
    Electronic Resource
    Nitrification of ammonium in different components of a flooded rice soil system (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 321-326 
    Details
    ISSN: 1432-0789
    Keywords: Nitrification ; Flooded rice soils ; Rhizosphere ; Rice variety ; Crop growth stage ; Organic amendment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrification associated with the various components [subsurface soil from unplanted and planted (rhizosphere) fields, standing water and surface soil from planted and unplanted fields and leaf sheath suspensions] of submerged rice paddies was examined in incubation experiments with solutions inoculated with soil or water samples. Substantial nitrification occurred in all samples, standing water and surface soil samples in particular, during their 40-day incubation with NH 4 + −N. Almost all the NH 4 + −N, disappeared during incubation with standing water, was recovered as NO inf3 sup- −N. This, compared to 70–80% from all soil samples and only 29% from leaf sheath suspensions. Significant loss of nitrogen, especially from leaf sheath suspensions, is probably due to nitrification-denitrification as evidenced by its complete recovery in the presence of N-Serve. Nitrification potential of the soil and water samples varied with the crop growth stage and was more pronounced at tillering and panicle inititation stages than at other stages. Nitrification potential of samples from green-manure-amended plots was distinctly less than that of samples from control and urea-amended plots. Most probable number (MPN) estimates of ammonium-oxidizing bacteria were always higher in surface soil in both planted and unplanted plots at all stages of crop growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335961
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  • 3
    Electronic Resource
    Electronic Resource
    Estimating microbial biomass N in soils with and without living roots: Limitations of a pre-extraction step (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 314-318 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass N ; Fumigation-extraction ; Pre-extraction ; Rhizosphere ; Roots ; Net-closed soil containers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Special net-closed soil containers were used in a pot experiment with low and high plant densities to give soil samples with and without roots. Soils from the containers were analysed either by the fumigation-extraction method or by a modified procedure starting with a pre-extraction and sieving step to remove plant roots from the samples. In the extracts NO 3 - -N, NH 4 + -N, organic N, and total N were measured. Microbial biomass N was calculated from the differences in total N in fumigated and unfumigated soils. Different plant densities had almost no influence on the values of the N compounds using either method. In soils with roots, significantly more organic N (and total N) was found by the fumigation-extraction method compared to soils without roots while no differences were obtained using pre-extractions and sieving. Though the organic N content in pre-extracts from soils with roots was significantly higher than from soils without roots, the NO 3 - -N and NH 4 + -N content was lower. Significant differences in biomass N in soils with and without roots were found only with the fumigation-extraction method. Biomass N levels calculated using the results after pre-extraction and sieving were about 50% lower than levels detected using fumigation-extraction alone. With the use of special net-closed soil containers, not only were soil samples produced with and without roots, but it was also possible to induce a rhizophere in the soils. A comparison of the two methods using these soils clearly demonstrated that the method used has profound influence on the final biomass N results. While higher “biomass” levels were found by fumigation-extraction in soils with roots, because root N becomes extractable after fumigation, the use of a pre-extraction and a sieving step may underestimate the total biomass N content due to the pre-extraction of microbial N (especially from rhizosphere microorganisms) from the sample. Nevertheless, pre-extraction and sieving followed by fumigation-extraction does seem to be the preferable method for biomass N measurement in comparative studies, because in most cases only minor errors will occur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00334909
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  • 4
    Electronic Resource
    Electronic Resource
    Nitrification and denitrification in the rhizosphere of rice: the detection of processes by a new multi-channel electrode (2000)
    Springer
    Biology and fertility of soils 31 (2000), S. 427-435 
    Details
    ISSN: 1432-0789
    Keywords: Key words Rice ; Nitrification ; Denitrification ; Rhizosphere ; Microelectrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  N turnover in flooded rice soils is characterized by a tight coupling between nitrification and denitrification. Nitrification is restricted to the millimetre-thin oxic surface layer while denitrification occurs in the adjacent anoxic soil. However, in planted rice soil O2 released from the rice roots may also support nitrification within the otherwise anoxic bulk soil. To locate root-associated nitrification and denitrification we constructed a new multi-channel microelectrode that measures NH4 +, NO2 –, and NO3 – at the same point. Unfertilized, unplanted rice microcosms developed an oxic-anoxic interface with nitrification taking place above and denitrification below ca. 1 mm depth. In unfertilized microcosms with rice plants, NH4 +, NO2 – and NO3 – could not be detected in the rhizosphere. Assimilation by the rice roots reduced the available N to a level where nitrification and denitrification virtually could not occur. However, a few hours after injecting (NH4)2HPO4 or urea, a high nitrification activity could be detected in the surface layer of planted microcosms and in a depth of 20–30 mm in the rooted soil. O2 concentrations of up to 150 μM were measured at the same depth, indicating O2 release from the rice roots. Nitrification occurred at a distance of 0–2 mm from the surface around individual roots, and denitrification occurred at a distance of 1.5–5.0 mm. Addition of urea to the floodwater of planted rice microcosms stimulated nitrification. Transpiration of the rice plants caused percolation of water resulting in a mass flow of NH4 + towards the roots, thus supporting nitrification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003749900190
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  • 5
    Electronic Resource
    Electronic Resource
    Measurement of pH at the root surface of red clover (Trifolium pratense) grown in soils differing in proton buffer capacity (1988)
    Springer
    Biology and fertility of soils 5 (1988), S. 295-298 
    Details
    ISSN: 1432-0789
    Keywords: pH measurement ; Rhizosphere ; SB electrodes ; Proton secretion of roots ; Red clover ; Rhizotrone ; Rhizobium spp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Measurements of pH were made at the root surface of Trifolium pratense, using Sb electrodes. Nodulated plants were grown in rhizotrones on a sandy soil free of carbonate and on a clay soil rich in carbonate. In the sandy soil, pH at the surface of root laterals was about 1 unit lower than in the bulk soil. The lowest pH values were found at the root tips. In the calcareous soil, pH measured at the root surface did not differ from pH in the bulk soil. This soil had a much higher H+ buffer capacity than the sandy soils. It seems likely that H+ ions excreted from the roots grown in the calcareous soil were directly neutralized by soil carbonate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262134
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  • 6
    Electronic Resource
    Electronic Resource
    Azospirillum — plant root associations: A review (1989)
    Springer
    Biology and fertility of soils 8 (1989), S. 356-368 
    Details
    ISSN: 1432-0789
    Keywords: Plant-root associations ; Azospirillum spp ; Rhizosphere ; Nitrogen fixation ; Acetylene reduction assay (ARA) ; Phytohormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Bacteria of the genus Azospirillum are extensively studied for their plant-growth promoting effect following inoculation. Physiological and biochemical studies of these diazotrophic bacteria are now benefiting from recent breakthroughs in the development of genetic tools for Azospirilum. Moreover, the identification and cloning of Azospirillum genes involved in N2 fixation, plant interaction, and phytohormone production have given new life to many research projects on Azospirillum. The finding that Azospirillum genes can complement specific mutations in other intensively studied rhizosphere bacteria like Rhizobia will certainly trigger the exploration of new areas in rhizosphere biology. Therefore a review of the Azospirillum-plant interactions is particularly timely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263169
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  • 7
    Electronic Resource
    Electronic Resource
    Denitrification in the rhizosphere of plants with inherently different aerenchyma formation: Wheat (Triticum aestivum) and rice (Oryza sativa) (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 215-219 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Air-filled porosity ; Rhizosphere ; Aerenchyma ; Rice ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Denitrification in the rhizosphere of wheat and rice was studied in relation to aerenchyma formation. Seedlings were grown in quartz silt amended with mineral nutrients at given bulk densities and water tensions. In adventitious wheat roots the formation of cortical lacunae was strongly dependent on soil aeration. Growing the wheat plants in dry (−20 kPa) and moist substrate (−2 kPa) established aerenchyma contents of 3% and 15%, respectively. Denitrification was measured after the introduction of equal moisture levels in the substrates of both treatments. The higher aerenchyma content of roots pregrown in the wetter substrate did not counteract denitrification in the rhizosphere which had doubled in this treatment. In contrast to the unspecific lysis of cortical cell walls, the well organized formation of aerenchyma in rice roots was independent of soil aeration. Root porosity averaged 14%. As in wheat, it was not related to denitrification. However, the level of denitrification per mg of root dry matter was about four times lower than that of wheat. The addition of decomposable organic matter (cellulose) to the substrate stimulated aerenchyma formation in rice and considerably increased denitrification. The results suggest that denitrification in the rhizosphere is independent of aerenchyma formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336228
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  • 8
    Electronic Resource
    Electronic Resource
    Chitinolytic and proteolytic activity of streptomycetes isolated from root-free soil, rhizosphere and mycorrhizosphere of pine (Pinus sylvestris L.) (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 268-272 
    Details
    ISSN: 1432-0789
    Keywords: Streptomycetes ; Chitinolytic ; Proteolytic activity ; Soil ; Pine roots ; Rhizosphere ; Pinus sylvestris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We tested 75 strains of Streptomyces spp. (25 taken from each environment of soil, rhizosphere, and mycorrhizosphere of pine, Pinus sylvestris L.) and all exhibited chitinolytic activity and hydrolysed gelatine and sodium caseinate in agar media. Enrichment of these media with glucose and NH4NO3 caused induction or stimulation of proteolytic Streptomyces spp. strains (80%) derived from root-free soil; inhibition of this activity was observed in most strains (92%) isolated from the root zone. The post-culture liquids of the rhizosphere strains cultured in the absence of glucose revealed a significantly higher proteolytic activity than those obtained from the root-free soil. The addition of glucose to the medium stimulated proteolytic activity in the post-culture broth of Streptomyces strains derived from soil and the mycorrhizosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336238
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  • 9
    Electronic Resource
    Electronic Resource
    Methanotrophic bacteria in the rhizosphere of rice microcosms and their effect on porewater methane concentration and methane emission (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 93-100 
    Details
    ISSN: 1432-0789
    Keywords: Wetland rice ; Rhizosphere ; Gas diffusion probe ; Methane profiles ; Methane oxidation ; Microcosms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract CH4 emission from irrigated rice field is one of the major sources in the global budget of atmoshperic CH4. Rates of CH4 emission depend on both CH4 production in anoxic parts of the soil and on CH4 oxidation at oxic-anoxic interfaces. In the present study we used planted and unplanted rice microcosms and characterized them by numbers of CH4-oxidizing bacteria (MOB), porewater CH4 and O2 concentrations and CH4 fluxes. Plant roots had a stimulating effect on both the number of total soil bacteria and CH4-oxidizing bacteria as determined by fluorescein isothiocyanate fluorescent staining and the most probable number technique, respectively. In the rhizosphere and on the root surface CH4-oxidizing bacteria were enriched during the growth period of tice, while their numbers remained constant in unplanted soils. In the presence of rice plants, the porewater CH4 concentration was significantly lower, with 0.1–0.4mM CH4, than in unplanted microcosms, with 0.5–0.7mM CH4. O2 was detected at depths of up to 16 mm in planted microcosms, whereas it had disappeared at a depth of 2 mm in the unplanted experiments. CH4 oxidation was determined as the difference between the CH4 emission rates under oxic (air) and anoxic (N2) headspace, and by inhibition experiments with C2H2. Flux measurements showed varying oxic emission rates of between 2.5 and 29.0 mmol CH4m-2 day-1. An average of 34% of the anoxically emitted CH4 was oxidized in the planted microcosms, which was surprisingly constant. The rice rhizosphere appeared to be an important oxic-anoxic interface, significantly reducing CH4 emission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336586
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  • 10
    Electronic Resource
    Electronic Resource
    Gram-negative bacterial flora on the root surface of wheat (Triticum aestivum) grown under different soil conditions (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 273-281 
    Details
    ISSN: 1432-0789
    Keywords: Key words Wheat ; (Triticum aestivum) ; Rhizosphere ; Soil microflora ; Gram-negative bacteria ; API 20NE ; Flavobacterium spp. ; Cytophaga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We identified 161 Gram-negative bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into seven groups based on major morphological and physiological properties. Taxonomic allocation of the groups was verified by guanine+cytosine contents of DNA. Except for one group, which may be assumed to include bacteria belonging to the genera Flavobacterium and Cytophaga, the various groups were taxonomically united. The distribution of the groups changed with soil improvement. Pseudomonads predominated in unimproved soil, but Flavobacterium and Cytophaga spp. were predominant in the most improved soil. As all the strains were non-fermentative by Hugh and Leifson‘s test, API 20NE identification was applied. However, many strains were misidentified by this system, especially in the Flavobacterium and Cytophaga spp. group. For ecological studies, the strains were classified to species level by the API 20 NE system and by the results of a combination of guanine+cytosine (mol%) and isoprenoid quinone data. The pattern of distribution of the bacteria on the root surface of wheat varied at species level within one genus depending on soil conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335955
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  • 11
    Electronic Resource
    Electronic Resource
    Endomycorrhizae in a newly cultivated acidic meadow: Effects of three years of barley cropping, tillage, lime, and phosphorus on root colonization and soil infectivity (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 160-165 
    Details
    ISSN: 1432-0789
    Keywords: Key words Hordeum vulgare ; Agricultural ecosystem ; Acidic soil ; Soil infectivity ; Endomycorrhizae ; Reduced tillage ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of mycorrhizae under disturbance created by crop production is not well understood. A 3-year experiment was undertaken on a nutrient-poor and acidic land that had last been cultivated in the early 1970s. We observed the effects of cropping spring barley (Hordeum vulgare L.) under four P-fertilizer levels and four levels of lime, in a minimum (rototillage), a reduced (chisel), or a conventional tillage system, on the mycorrhizal receptiveness of the host (maximum level of mycorrhizal colonization, as measured at harvest) and soil infectivity most probable number method. The host receptiveness decreased with time, while crop yields and soil infectivity increased simultaneously with time. Liming increased mycorrhizal colonization of barley roots and soil infectivity. P additions decreased root colonization but did not significantly affect the most probable number values. Slightly higher soil infectivity estimates were found under reduced tillage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335928
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  • 12
    Electronic Resource
    Electronic Resource
    Solubilization of hydroxyapatite by Enterobacter agglomerans and cloned Escherichia coli in culture medium (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 347-352 
    Details
    ISSN: 1432-0789
    Keywords: Key words Phosphate-solubilizing bacteria ; Hydroxyapatite ; Enterobacter agglomerans ; Organic acids ; Phosphate-solubilizing genes ; Rhizosphere ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphate-solubilizing bacteria (PSB) possessing the ability to solubilize insoluble inorganic phosphate were isolated from the rhizosphere soil of wheat. A laboratory study was conducted to investigate the solubilization of phosphate by a known PSB, Enterobacter agglomerans, and by a genetically manipulated bacterium, Escherichia coli. A second laboratory study investigated the release of P from E. agglomerans compared with known acids. For the first laboratory study, a cosmid (pHC79) library of phosphate-solubilizing gene(s) from E. agglomerans chromosome DNA was constructed in E. coli JM109. The clone JM109 (pKKY) showing phosphate solubilization properties was screened on standard medium containing hydroxyapatite (HY). The P concentration significantly increased at 5 and 10 days for JM109 (pKKY) compared with JM109 (pHC79), the control. Although the P concentration increased, there was no significant change in their pHs. Furthermore, an increase in colony-forming units (CFUs) was seen at 5 and 10 days for JM109 (pKKY) but not for JM109 (pHC79). Artificial acidification of the culture medium with HCl, citric acid, oxalic acid, and lactic acid was achieved by shaking for 48h. Acidification with these selected acids solubilized more HY than E. agglomerans growing for 42h at similar pHs. However, a high P concentration was measured in culture medium with E. agglomerans growing for 84h despite similar pHs. Our results suggest that acid production may play an important role in HY solubilization, but is not the sole reason for the increase in P concentration in culture medium.
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    URL: http://dx.doi.org/10.1007/s003740050256
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  • 13
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    Relative importance of motility and antibiosis in the rhizoplane competence of a biocontrol agent Pseudomonas fluorescens MelRC2Rif (1997)
    Springer
    Biology and fertility of soils 25 (1997), S. 416-420 
    Details
    ISSN: 1432-0789
    Keywords: Key wordsPseudomonas fluorescens ; MelRC2Rif ; Motility ; Antibiosis ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Mutants defective in motility or antibiotics production were obtained by Tn5 mutagenesis of a biocontrol agent Pseudomonas fluorescens MelRC2Rif (wt). Tomato or melon seeds were co-inoculated with a Tn5 mutant and wt in a 1:1 ratio and then grown in soil for 10 days. There was no change in ratios of Tn5 mutants defective in antibiosis to wt in the process of rhizoplane colonization, suggesting little contribution of in vitro antibiosis to the rhizoplane competence of P. fluorescens MelRC2Rif. Similar results were also obtained when seeds treated with bacteria were planted in soil artificially infested with fungal pathogens. In contrast, ratios of Tn5 mutants defective in motility to wt significantly decreased, suggesting the contribution of motility to the rhizoplane competence of this bacterium. When a non-motile Tn5 mutant and wt were co-inoculated into soil at a matric potential of pF 2.3 (–20 kPa) and plants were then grown, there was no change in the ratio in rhizoplane colonization, suggesting that motility might have a role in the movement along roots but an insignificant role in the movement from bulk soil towards roots. When they were co-inoculated into 0.2% water agar (WA) instead of soil, a remarkable decline in ratios was detected. Thus it was soil structure that hindered the efficiency of motility. Time course enumeration of rhizoplane colonization of tomatoes grown in WA revealed that motility was an important means of movement towards and/or along roots rather than the multiplication on roots.
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    URL: http://dx.doi.org/10.1007/s003740050334
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  • 14
    Electronic Resource
    Electronic Resource
    Phosphatase activity in the rhizosphere and its relation to the depletion of soil organic phosphorus (1987)
    Springer
    Biology and fertility of soils 3 (1987), S. 199-204 
    Details
    ISSN: 1432-0789
    Keywords: Phosphatases ; Rhizosphere ; Organic phosphorus ; Allium cepa ; Brassica oleracea ; Triticum aestivum ; Trifolium alexandrinum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The distribution of phosphatase activity and of phosphate fractions of the soil in the proximity of roots was studied in order to evaluate the significance of phosphatases in P nutrition of various plants (Brassica oleracea, Allium cepa, Triticum aestivum, Trifolium alexandrinum). A considerable increase in both acid and alkaline phosphatase activity in all the four soil-root interfaces was observed. Maximum distances from the root surface at which activity increases were observed ranged from 2.0 mm to 3.1 mm for acid phosphatase and from 1.2 mm to 1.6 mm for alkaline phosphatase. The increase in phosphatase activity depended upon plant age, plant species and soil type. A significant correlation was noticed between the depletion of organic P and phosphatase activity in the rhizosphere soil of wheat (r = 0.99**) and clover (r = 0.97**). The maximum organic P depletion was 65% in clover and 86% in wheat, which was observed within a distance from the root of 0.8 mm in clover and 1.5 mm in wheat. Both the phosphatases in combination appear to be responsible for the depletion of organic P.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00640630
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  • 15
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    Comparing microbial biomass, denitrification enzyme activity, and numbers of nitrifiers in the rhizospheres of Pinus sylvestris, Picea abies and Betula pendula seedlings by microscale methods (1999)
    Springer
    Biology and fertility of soils 30 (1999), S. 14-19 
    Details
    ISSN: 1432-0789
    Keywords: Key words Tree species ; Rhizosphere ; Microbial biomass ; Denitrification enzyme activity ; Autotrophic nitrifiers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Flushes of C and N from fumigation-extraction (FE-C and FE-N, respectively), substrate-induced respiration (SIR), denitrification enzyme activity (DEA) and numbers of NH4 + and NO2 – oxidizers were studied in the rhizospheres of Scots pine (Pinus sylvestris L.), Norway spruce [(Picea abies (L.) Karsten] and silver birch (Betula pendula Roth) seedlings growing in soil from a field afforestation site. The rhizosphere was defined as the soil adhering to the roots when they were carefully separated from the rest of the soil in the pots, termed as "planted bulk soil". Soil in unplanted pots was used as control soil. All seedlings had been grown from seed and had been infected by the natural mycorrhizas of soil. Overall, roots of all tree species tended to increase FE-C, FE-N, SIR and DEA compared to the unplanted soil, and the increase was higher in the rhizosphere than in the planted bulk soil. In the rhizospheres tree species did not differ in their effect on FE-C, FE-N and DEA, but SIR was lowest under spruce. In the planted bulk soils FE-C and SIR were lowest under spruce. The planted bulk soils differed probably because the roots of spruce did not extend as far in the pot as those of pine and birch. The numbers of both NH4 + and NO2 –oxidizers, determined by the most probable number method, were either unaffected or decreased by roots, with the exception of the spruce rhizosphere, where numbers of both were increased.
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    URL: http://dx.doi.org/10.1007/s003740050581
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  • 16
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    The "oxygen paradox" of dinitrogen-fixing bacteria (2000)
    Springer
    Biology and fertility of soils 30 (2000), S. 363-373 
    Details
    ISSN: 1432-0789
    Keywords: Key words Azospirillum species ; Oxygen paradox ; Nitrogen fixation ; Rhizosphere ; Nitrogenase complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  N2 fixation by aerobic bacteria is a very energy demanding process, requiring efficient oxidative phosphorylation, while O2 is toxic for the nitrogenase complex. N2-fixing bacteria have evolved a variety of strategies to cope with this apparent "O2 paradox". This review compares strategies that azospirilla and other well-known N2-fixing soil bacteria use to overcome this O2 paradox. Attention will be given to the relationships between the natural habitat of these soil bacteria and their prevailing adaptations. In view of this knowledge the following questions will be addressed: are the specific adaptations observed in azospirilla sufficient to allow optimal proliferation and N2 fixation in their natural habitat? Could improving the O2 tolerance of the N2-fixing process contribute to the development of more efficient strains for the inoculation of plants?
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050017
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  • 17
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    Microsensor analysis of oxygen and pH in the rice rhizosphere under field and laboratory conditions (1999)
    Springer
    Biology and fertility of soils 29 (1999), S. 379-385 
    Details
    ISSN: 1432-0789
    Keywords: Key words Oxygen ; pH ; Rhizosphere ; Microsensor ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  O2 and pH microsensors were used to analyse the microdistribution of O2 and pH inside and outside roots of lowland rice (Oryza sativa L.). The roots of 3-week-old transplants had O2 concentrations of about 20% air saturation at the surface, but due to a high rate of O2 consumption in the rhizosphere, the oxic region only extended about 0.4 mm into the surrounding soil. Also the fine lateral roots created an oxic zone extending about 0.15 mm into the soil. The O2 concentration within the roots approached air saturation close to the base, but only about 40–60% of air saturation in a region about 8 cm below the base where lateral rootlets were present. A shift from air to N2 around the leaves led to a drop of 50% in the O2 concentration after 12 min at a distance of 8.5 cm from the base. Flowering plants did not export O2 to the soil from the majority of their roots, but high microbial activity was present in a very thin biofilm covering the root surface. A brown colour around the thin lateral roots indicated some O2 export from these also during flowering. No oxidized zone was present around the roots at later stages of crop growth. The roots caused only minor minima in pH (〈0.2 pH units) in the rhizosphere as compared to the bulk soil. Illumination of the plants had no effect on rhizosphere pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050568
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  • 18
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    Effect of bulk density and soil water tension on denitrification in the rhizosphere of spring wheat (Triticum vulgare (1987)
    Springer
    Biology and fertility of soils 5 (1987), S. 181-187 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Rhizosphere ; Bulk density ; Water tension ; Acetylene inhibition method ; Triticum vulgare
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Pot experiments were carried out to study the influence of bulk density (D b), soil water tension (pF) and presence of plants (spring wheat) on denitrification in a low-humus Bt-horizon of a udalf. Pots of only 5-cm depth were found to be most suitable for the experiments when using the acetylene inhibition method. Almost homogeneous soil compaction between 1.1 and 1.6g soil cm−3 was achieved by a Proctor tamper. Water tensions were adjusted by means of ceramic plates on which negative pressure was applied. No denitrification was detected in unplanted pots. With planted pots and increasing bulk density denitrification increased more in pots with 14-day-old plants than in pots with 7-day-old plants. With 14-day-old plants N2O emission pot−1 increased steadily from 2 μmol at D b 1.1 to 8 μmol at D b 1.6, when soil moisture was adjusted to pF 1.5, although root growth was impaired by higher bulk density. From an experiment with different bulk densities and water tensions it could be deduced that the air-filled porosity ultimately determined the rate of denitrification. When low water tension was applied for a longer period, water tension had an overriding effect on total denitrification. Denitrification intensity, however, i.e. the amount of N2O g−1 root fresh weight, was highest when low water tension was accompanied by high bulk density. The results suggest that the increase in denitrification intensity at oxygen stress is partly due to higher root exudation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00256898
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  • 19
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    Nodulation competition among Bradyrhizobium japonicum strains as influenced by rhizosphere bacteria and iron availability (1989)
    Springer
    Biology and fertility of soils 7 (1989), S. 108-112 
    Details
    ISSN: 1432-0789
    Keywords: Bradyrhizobium japonicum ; Glycine max ; Soil inoculation ; Nodulation ; Rhizosphere ; Rhizobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Bacteria isolated from the root zones of field-grown soybean plants [Glycine max (L.) Merr.] were examined in a series of glasshouse experiments for an ability to affect nodulation competition among three strains of Bradyrhizobium japonicum (USDA 31, USDA 110, and USDA 123). Inocula applied at planting contained competing strains of B. japonicum with or without one of eleven isolates of rhizosphere bacteria. Tap-root nodules were harvested 28 days after planting, and nodule occupancies were determined for the bradyrhizobia strains originally applied. Under conditions of low iron availability, five isolates (four Pseudomonas spp. plus one Serratia sp.) caused significant changes in nodule occupancy relative to the corresponding control which was not inoculated with rhizosphere bacteria. During subsequent glasshouse experiments designed to verify and further characterize these effects, three fluorescent Pseudomonas spp. consistently altered nodulation competition among certain combinations of bradyrhizobia strains when the rooting medium did not contain added iron. This alteration typically reflected enhanced nodulation by USDA 110. Two of these isolates produced similar, although less pronounced, effects when ferric hydroxide was added to the rooting medium. The results suggest that certain rhizosphere bacteria, particularly fluorescent Pseudomonas spp., can affect nodulation competition among strains of R. japonicum. An additional implication is that iron availability may be an important factor modifying interactions involving the soybean plant, B. japonicum, and associated microorganisms in the host rhizosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292567
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  • 20
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    Stimulation of root exudation of rice seedlings by Azospirillum strains: carbon budget under gnotobiotic conditions (1987)
    Springer
    Biology and fertility of soils 4 (1987), S. 9-14 
    Details
    ISSN: 1432-0789
    Keywords: Rhizosphere ; Nitrogen fixation ; Root exudates ; Soil bacteria ; Carbon budget ; Rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The association of rice seedlings (cv. Delta) with different strains of Azospirillum was studied under monoxenic conditions in the dark. Axenic 3-day-old seedlings were obtained on a C- and N-free medium and inoculated with 6 · 107 bacteria per plant in a closed vial. Seven days later, different components of a carbon budget were evaluated on them and on sterile controls: respired CO2, carbon of shoot and roots, bacterial and soluble carbon in the medium. Two strains (A. lipoferum 4B and A. brasilense A95) isolated from the rhizosphere of rice caused an increase in exudation, + 36% and + 17% respectively compared with sterile control. Shoot carbon incorporation and respiration were reduced by inoculation. A third strain (A. brasilense R07) caused no significant change in exudation. A. lipoferum B7C isolated from maize did not stimulate rice exudation either. We further investigated a possible effect of nitrogen fixation on this phenomenon: inhibition of nitrogen fixation by 10% C2H2 did not modify the extent of C exudation by rice associated with A. lipoferum 4B or with the non-motile A. lipoferum 4T.
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    URL: http://dx.doi.org/10.1007/BF00280344
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  • 21
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    A comparison of microbial-feeding nematodes and protozoa in the rhizosphere of different plants (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 83-88 
    Details
    ISSN: 1432-0789
    Keywords: Nematodes ; Protozoa ; Rhizosphere ; Nutrient cycling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The biomass of microbial-feeding nematodes and protozoa was measured in the rhizospheres of peas, barley, grass and turnips grown for 10 weeks in pots containing a clay-loam soil; in the rhizospheres of peas and barley grown for 3 weeks in a sandy soil; and in the rhizosphere of barley grown for 11 weeks in an unfertilised and a fertilised clay-loam soil. The nematode biomass was consistently larger in the rhizosphere of all plants in both soils than in the bulk soil, but the protozoa biomass showed a rhizosphere effect only under pea and fertilised barley. The biomass of nematodes in the rhizosphere (1.2–22.3 μg dry weight g-1 dry soil) was greater than the biomass of protozoa (0.1–3.2 μg g-1), and greater under pea〉barley〉grass〉turnip. It is suggested that nematodes are more able to exploit low bacterial densities than protozoa and that they initially migrate into the rhizosphere from the bulk soil. In samples of potato rhizosphere from field-grown plants, the nematode biomass was also greater than the active and total protozoan biomass. It is argued that in the rhizosphere the biomass of microbially feeding nematodes exceeds that of protozoa and that nematodes are more important in terms of nutrient cycling.
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    URL: http://dx.doi.org/10.1007/BF00335867
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  • 22
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    Short-term measurements of uptake of nitrogen fixed in the rhizospheres of sorghum (Sorghum bicolor) and millet (Pennisetum americanum) (1988)
    Springer
    Biology and fertility of soils 7 (1988), S. 11-15 
    Details
    ISSN: 1432-0789
    Keywords: 15N ; N2 fixation ; Rhizosphere ; Sorghum bicolor ; Pennisetum americanum ; Acetylene reduction assay (ARA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In a series of short-term experiments root systems of young sorghum and millet plants inoculated with N2-fixing bacteria were exposed to 15N2-enriched atmospheres for 72 h. The plants were grown in a normal atmosphere for up to 22 days after the end of the exposure to allow them to take up the fixed N2. Environmental conditions and genotypes of sorghum and millet were selected to maximise N2-fixation in the rhizosphere. Detectable amounts of fixed N (〉 16 μg/plant) were rapidly incorporated into sorghum plants grown in a sand/farmyard manure medium, but measurable fixation was found on only one occasion in plants grown in soil. N2 fixation was detectable in some experiments with soil-grown millet plants but the amounts were small (2–4 μg/plant) and represented less than 1 % of plant N accumulated over the same period. In many cases there was no detectable 15N2 incorporation despite measurable increases in ethylene concentration found during an acetylene reduction assay.
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    URL: http://dx.doi.org/10.1007/BF00260725
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  • 23
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    The microarthropod fauna associated with a deep rooted legume, Prosopis glandulosa, in the Chihuahuan Desert (1989)
    Springer
    Biology and fertility of soils 7 (1989), S. 330-335 
    Details
    ISSN: 1432-0789
    Keywords: Prosopis glandulosa ; Rhizosphere ; Mites ; Collembolans ; Chihuahuan Desert
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The rhizosphere microarthropod fauna of a woody, deep-rooted legume, Prosopis glandulosa, was sampled at four sites in the northern Chihuahuan Desert and compared with the rhizosphere microarthropod fauna of a co-dominant shrub, Larrea tridentata. Prostigmatid mites (Speleorchestes sp.,Neognathus sp., Rhagidia sp., Tydaeolus sp., Steneotarsonemus sp., Tarsonemus sp., Nanorchestes sp., Gordialycus sp.), the cryptostigmatid mites (Bankisonoma ovata and Passalozetes neomexicanus), the mesostigmatid (Protogamasellus mica), and the collembolan (Brachystomella arida) characterized the fauna at depths greater than 1 m. Microarthropods were recovered from soils at a depth of 13 m at the edge of a dry lake and at depths of 7 m in a dry wash which were pre-European man P. glandulosa habitats. In habitats where P. glandulosa is a recent invader, root depth and microarthropods were less than 3 m. In most habitats, population densites of microarthropods at depths 0.5 m were more than 100 times those at depths ≫ 0.5 m. Population densities of microarthropods associated with P. glandulosa growing at the edge of a dry wash were not significantly smaller at 0.5−1.0 m depth than at 0−0.5 m. The deep-rhizosphere microarthropod fauna is a reduced subset of the fauna of surficial soils, suggesting that this fauna plays a role in decomposition and mineralization processes functionally similar to that of microarthropods in surficial soils.
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    URL: http://dx.doi.org/10.1007/BF00257828
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  • 24
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    Distribution of microbial biomass across the rhizosphere of barley (Hordeum vulgare L.) in soils (1989)
    Springer
    Biology and fertility of soils 7 (1989), S. 341-345 
    Details
    ISSN: 1432-0789
    Keywords: ATP content ; Bulk soil ; CO2 production ; Mineral N ; Nitrification inhibitor ; Rhizosphere ; Sewage sludge ; Hordeum vulgare
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The microbial activity at the soil-root interface (rhizosphere) of barley was examined using a rhizobox system. In this system, the soil was placed in several compartments separated from each other by a 500-mesh nylon cloth. Plants were grown in the central compartment and after a 2-month growing period the roots were still confined to this compartment. The soil from each compartment was then analyzed for ATP, NO3 /−, total N, total C and CO2 production. The increase in ATP concentration was found in a range of 4 mm around the roots. The ATP content and CO2 production across the rhizosphere were correlated in all the soils used, but changes in NO3 − were not correlated with ATP changes. The range of NO3 − change was wider than that of the ATP change, indicating that NO3 − production is not influenced by the biological activity in the rhizosphere.
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    URL: http://dx.doi.org/10.1007/BF00257830
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  • 25
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    Gram-positive bacterial flora on the root surface of wheat (Triticum aestivum L.) grown under different soil conditions (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 121-125 
    Details
    ISSN: 1432-0789
    Keywords: Key words Wheat ; Rhizosphere ; Soil Microflora ; Gram-positive Bacteria ; Coryneform Bacteria ; Arthrobacter spp. ; Mol% G+C ; Diaminopimelic acid ; DAP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We identified 108 Gram-positive bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into four groups based on morphological and physiological characteristics, but most appeared to be coryneform. The taxonomic position of the various groups was verified by the guanine+cytosine DNA contents of the strains. In general, the ranges of these values agreed with those described for the respective taxonomic positions in the literature, with a few exceptions. With soil improvement the distribution of the various groups on the root surface changed, with the coryneform group becoming dominant. This group was further divided into five subgroups, according to cell wall components, cellulose-decomposition, and morphological characteristics, and were identified to genus level. The distribution of these subgroups on the root surface of wheat did not alter with soil improvement. The genus Arthrobacter, the dominant subgroup, predominated in every plot.
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    URL: http://dx.doi.org/10.1007/BF00336051
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  • 26
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    Azospirillum spp. participation in dry matter partitioning in grasses at the whole plant level (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 435-440 
    Details
    ISSN: 1432-0789
    Keywords: Key wordsAzospirillum spp. ; Crop plants ; Plant growth-promoting rhizobacteria ; Plant inoculation ; Rhizosphere ; Shoot-to-root ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant growth-promoting rhizobacteria, particularly those from the genus Azospirillum spp., may affect root functions such as growth and nutrient/water uptake, which in turn may affect shoot growth. Calculations based on data from literature on shoot and root mass of crop grasses (79 plant/bacteria associations were analyzed) revealed that inoculation with Azospirillum spp. increased the shoot-to-root (S/R) ratio in about half of reported cases and decreased the S/R ratio in the other half. In 11 of 35 cases, the S/R ratio increased when the shoot mass increased more than the root mass. In 23 of 35 cases, the root mass did not increase, yet the S/R ratio still increased. Thus, the increase in the S/R ratio indicated that shoot growth responds to inoculation more than root growth. A decrease in the S/R ratio occurred when (a) root growth dominated shoot growth even though both increased (16 of 36 cases), or (b) root growth either increased or remained unchanged, and shoot growth was either unaffected or even decreased (19 of 36 cases). This analysis suggests that: (a) Azospirillum spp. participates in the partitioning of dry matter (both carbon compounds and minerals) at the whole plant level by affecting root functions, and (b) the bacteria affect crop grass through multiple mechanisms operating during plant development.
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    URL: http://dx.doi.org/10.1007/BF00335919
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  • 27
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    Gram-positive bacterial flora on the root surface of wheat (Triticum aestivum L.) grown under different soil conditions (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 121-125 
    Details
    ISSN: 1432-0789
    Keywords: Wheat ; Rhizosphere ; Soil Microflora ; Gram-positive Bacteria ; Coryneform Bacteria ; Arthrobacter spp. ; Mol% G+C ; Diaminopimelic acid ; DAP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We identified 108 Gram-positive bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into four groups based on morphological and physiological characteristics, but most appeared to be coryneform. The taxonomic position of the various groups was verified by the guanine+cytosine DNA contents of the strains. In general, the ranges of these values agreed with those described for the respective taxonomic positions in the literature, with a few exceptions. With soil improvement the distribution of the various groups on the root surface changed, with the coryneform group becoming dominant. This group was further divided into five subgroups, according to cell wall components, cellulose-decomposition, and morphological characteristics, and were identified to genus level. The distribution of these subgroups on the root surface of wheat did not alter with soil improvement. The genus Arthrobacter, the dominant subgroup, predominated in every plot.
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  • 28
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    Soil protozoa and forest tree growth: non-nutritional effects and interaction with mycorrhizae (1995)
    Springer
    Biology and fertility of soils 20 (1995), S. 263-269 
    Details
    ISSN: 1432-0789
    Keywords: Ectomycorrhiza ; Lactarius ; Minearl nutrition ; Picea abies ; Plant growth ; Protozoa ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Mycorrhizal (Lactarius rufus Fr.) and non-mycorrhizal Norway spruce seedlings (Picea abies Karst.) were grown in a sand culture and inoculated with protozoa (naked amoebae and flagellates) extracted from native forest soil or with protozoa grown on agar cultures. A soil suspension from which the protozoa were eliminated by filtration or chloroform fumigation was used as a control. After 19 weeks of growth in a climate chamber at 20–22°C, the seedlings were harvested. Protozoa reduced the number of bacterial colony-forming units extracted from the rhizoplane of both non-mycorrhizal and mycorrhizal seedlings and significantly increased seedling growth. However, concentrations of mineral nutrients in needles were not increased in seedlings with protozoan treatment. It is concluded that the increased growth of seedling was not caused by nutrients released during amoebal grazing on rhizosphere micro-organisms. The protozoa presumably affected plant physiological processes, either directly, via production of phytohormones, or indirectly, via modification of the structure and performance of the rhizosphere microflora and their impact on plant growth. Mycorrhizal colonization significantly increased the abundance of naked amoebae at the rhizoplane. Our observations indicate that protozoa in the rhizosphere interact significantly with mycorrhizae.
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    URL: http://dx.doi.org/10.1007/BF00336088
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    Plant and soil responses to mycorrhizal fungi and rhizobacteria in nodulated or nitrate-fertilized peas (Pisum sativum L.) (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 164-168 
    Details
    ISSN: 1432-0789
    Keywords: Key wordsBacillus ; Glomus ; Mycorrhiza ; Pisum ; sativum ; Plant response ; Rhizosphere ; Root nodule ; Soil aggregation ; Soil pH ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rhizosphere organisms affect plant development and soil stability. This study was conducted to determine the effects of a vesicular-arbuscular mycorrhizal (VAM) fungus [Glomus mosseae (Nicol. &〉; Gerd.) Gerd. and Trappe] and a rhizobacterium (Bacillus sp.) on nitrate-fertilized or nodulated pea (Pisum sativum L.) plants and on the status of water-stable soil aggregates. The plants were grown in pots in a yellow clay-loam soil, and inoculated with the VAM fungus and the rhizobacterium, with one of the two, or with neither. The Bacillus sp. and G. mosseae did not affect shoot dry mass in nodulated plants. Under N fertilization, the VAM fungus enhanced plant growth, while the rhizobacterium inhibited shoot growth, VAM root colonization, and nodule formation, but enhanced the root:shoot and the seed:shoot ratios. The inhibition of shoot growth and of root colonization appeared to be related. The water stability and pH of the VAM soils were higher than those of the non-VAM soils. The rhizobacterium enhanced the water-stable aggregate status in the non-VAM soils only. Under both N-nutrition regimes, the soils had the greatest proportion of the water-stable aggregates when inoculated with both rhizo-organisms and the lowest when colonized by neither. The two rhizo-organisms affected both plants and soil, and these effects were modified by the source of N input through N2 fixation or fertilization.
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    URL: http://dx.doi.org/10.1007/s003740050225
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    Enhanced dissolution of phosphate rocks in the rhizosphere (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 169-174 
    Details
    ISSN: 1432-0789
    Keywords: Key words Dissolution ; Open leaching ; Organic acids ; Phosphate rocks ; Plant uptake ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Dissolution of two phosphate rocks (PRS) which vary in their chemical reactivity was examined using two soils in the absence (closed-incubation and open-leaching) and presence (thin-layer) of plants. Greater dissolution was obtained in the presence than in the absence of plants. In the absence of plants, open-leaching resulted in higher dissolution than the closed-incubation system. Removal of the dissolved Ca from the zone of PR dissolution is considered to be the main reason for the increased dissolution in the open-leaching columns. In the case of the thin-layer experiment, removal of Ca and P through plant uptake and the supply of protons (H+) through the release of organic acids are considered to be the main reasons for the enhanced dissolution of PRs in the rhizosphere.
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    URL: http://dx.doi.org/10.1007/s003740050226
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    Kinetic properties and stability of potato acid phosphatase immobilized on Ca-polygalacturonate (1998)
    Springer
    Biology and fertility of soils 27 (1998), S. 97-103 
    Details
    ISSN: 1432-0789
    Keywords: Key words Potato acid phosphatase ; Ca-Polygalacturonate ; Rhizosphere ; Mucigel ; Michaelis-Menten kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Acid phosphatase from potato was adsorbed and immobilized on a pre-formed network of Ca-polygalacturonate, a substrate which has a composition and morphology similar to the mucigel present at the root-soil interface. The influence of different types of organic buffers on enzyme adsorption and activity was investigated. The highest enzyme activity, for free and adsorbed enzyme, was obtained with Na-maleate buffer at pH 6.0, which was used for all subsequent experiments. The Michaelis-Menten kinetic parameters, Vmax and Km, were determined for free and adsorbed phosphatase. Vmax showed a 60% decrease upon adsorption (2.09±0.30 U/mg, for the soluble form and 0.84±0.15 U/mg, for the adsorbed enzyme), whereas Km increased from 0.49±0.15 mM for the free enzyme to 0.99±0.20 mM for adsorbed phosphatase. Phosphatase adsorption decreased as the concentration of NaCl increased, indicating that the enzyme is bound to the carrier gel through coulombic interactions. Adsorption increased stability of the enzyme as compared with the free enzyme (t 1/2 of the activity was 9.4 days and 5.8 days, respectively), but increased thermal and proteolytic inactivation. The pH/activity profile revealed no change in terms of shape or optimum pH (4.5) upon adsorption of the enzyme. These results indicate that adsorption of acid phosphatase on Ca-polygalacturonate induces changes in the kinetic properties and stability of the enzyme, and the same type of response can be extrapolated from these results for acid phosphatases of the rhizosphere.
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    URL: http://dx.doi.org/10.1007/s003740050406
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    The number of bacteria in the rhizosphere during plant development: relating colony-forming units to different reference units (1999)
    Springer
    Biology and fertility of soils 28 (1999), S. 285-291 
    Details
    ISSN: 1432-0789
    Keywords: Key words Chrysanthemum ; Rhizosphere ; Rhizobacteria ; Root age ; Reference unit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The number of bacteria was determined during the growth of chrysanthemum plants on young (tip) and old (base) root parts. We assessed if the same conclusions could be drawn on the dynamics of bacterial populations during plant development when different reference units were used to express the bacterial counts. The results indicated that the total number of bacteria on the base decreased significantly during plant development, when expressed per root length, per root fresh weight or per root surface. The number of bacteria on the tip only decreased significantly when expressed per root length. Using the unit of dry weight of adhering soil, contradictory results were obtained for both base and tip; in general, the number of bacteria increased significantly during plant development. Thus, different reference units may lead to different conclusions. Root surface seemed to be the best unit to use, but the use of this unit requires time-consuming measurements. Regression analyses indicated that the reference unit "root surface" was highly correlated with root fresh weight (R 2=93%). Thus, once this relation is determined, the less time-consuming unit can be measured in the experimental work. To analyse the data, the colony-forming units should be expressed per root surface. Besides bacterial numbers during plant development, we assessed whether the bacterial populations collected showed different growth rates on agar plates. The growth rates of bacteria from the tip and base and different development stages of the plants showed differences, indicating differences in the metabolic state of the collected populations.
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    Solubilization of inorganic phosphates and growth emergence of wheat as affected by Azotobacter chroococcum mutants (1999)
    Springer
    Biology and fertility of soils 28 (1999), S. 301-305 
    Details
    ISSN: 1432-0789
    Keywords: Key words Azotobacter chroococcum ; Inorganic phosphate solubilization ; Indole acetic acid ; Growth emergence ; Wheat ; Phytohormone production ; Rhizosphere ; Phosphate solubilizing bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Phosphate-solubilizing strains of A. chroococcum isolated from the wheat rhizosphere were evaluated for their ability to solubilize tricalcium phosphate (TCP), Mussoorie rock phosphate (MRP) and also for indole-acetic-acid (IAA) production. Strains were selected on the basis of the clearance zone on solid agar media of Pikovskaya and Jensen's media containing TCP, and phosphate solubilization in Jensen's liquid culture medium containing both TCP and MRP. Mutants of the best phosphate-solubilizing (TCP 1.52 μg ml–1 MRP 0.19 μg ml–1), IAA-producing A. chroococum strain P-4, were developed and screened for P solubilization and phytohormone production. Five mutants solubilized more P (in the range of 1.5–1.7 μg/ml–1 of TCP and 0.19–0.22 μg ml–1 of MRP) than the parent strains. In vitro growth emergence studies of three wheat varieties, viz. C-306, WH-542 and HD-2009, showed better performance with phosphate-solubilizing mutants than with the parent strain.
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    Phosphate-solubilizing microorganisms associated with the rhizosphere of mangroves in a semiarid coastal lagoon (2000)
    Springer
    Biology and fertility of soils 30 (2000), S. 460-468 
    Details
    ISSN: 1432-0789
    Keywords: Key words Mangrove ; Bacillus spp. ; Enterobacter spp. ; Inorganic phosphate-solubilizing microorganisms ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The phosphate-solubilizing potential of the rhizosphere microbial community in mangroves was demonstrated when culture media supplemented with insoluble, tribasic calcium phosphate, and incubated with roots of black (Avicennia germinans L.) and white [Laguncularia racemosa (L.) Gaertn.] mangrove became transparent after a few days of incubation. Thirteen phosphate-solubilizing bacterial strains were isolated from the rhizosphere of both species of mangroves: Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus atrophaeus, Paenibacillus macerans, Vibrio proteolyticus, Xanthobacter agilis, Enterobacter aerogenes, Enterobacter taylorae, Enterobacter asburiae, Kluyvera cryocrescens, Pseudomonas stutzeri, and Chryseomonas luteola. One bacterial isolate could not be identified. The rhizosphere of black mangroves also yielded the fungus Aspergillus niger. The phosphate-solubilizing activity of the isolates was first qualitatively evaluated by the formation of halos (clear zones) around the colonies growing on solid medium containing tribasic calcium phosphate as a sole phosphorus source. Spectrophotometric quantification of phosphate solubilization showed that all bacterial species and A. niger solubilized insoluble phosphate well in a liquid medium, and that V. proteolyticus was the most active solubilizing species among the bacteria. Gas chromatographic analyses of cell-free spent culture medium from the various bacteria demonstrated the presence of 11 identified, and several unidentified, volatile and nonvolatile organic acids. Those most commonly produced by different species were lactic, succinic, isovaleric, isobutyric, and acetic acids. Most of the bacterial species produced more than one organic acid whereas A. niger produced only succinic acid. We propose the production of organic acids by these mangrove rhizosphere microorganisms as a possible mechanism involved in the solubilization of insoluble calcium phosphate.
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    Azospirillum spp. participation in dry matter partitioning in grasses at the whole plant level (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 435-440 
    Details
    ISSN: 1432-0789
    Keywords: Azospirillum spp. ; Crop plants ; Plant growth-promoting rhizobacteria ; Plant inoculation ; Rhizosphere ; Shoot-to-root ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant growth-promoting rhizobacteria, particularly those from the genus Azospirillum spp., may affect root functions such as growth and nutrient/water uptake, which in turn may affect shoot growth. Calculations based on data from literature on shoot and root mass of crop grasses (79 plant/bacteria associations were analyzed) revealed that inoculation with Azospirillum spp. increased the shoot-to-root (S/R) ratio in about half of reported cases and decreased the S/R ratio in the other half. In 11 of 35 cases, the S/R ratio increased when the shoot mass increased more than the root mass. In 23 of 35 cases, the root mass did not increase, yet the S/R ratio still increased. Thus, the increase in the S/R ratio indicated that shoot growth responds to inoculation more than root growth. A decrease in the S/R ratio occurred when (a) root growth dominated shoot growth even though both increased (16 of 36 cases), or (b) root growth either increased or remained unchanged, and shoot growth was either unaffected or even decreased (19 of 36 cases). This analysis suggests that: (a) Azospirillum spp. participates in the partitioning of dry matter (both carbon compounds and minerals) at the whole plant level by affecting root functions, and (b) the bacteria affect crop grass through multiple mechanisms operating during plant development.
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    URL: http://dx.doi.org/10.1007/BF00335919
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    Methane-oxidizing activities and methanotrophic populations associated with wetland rice plants (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 261-265 
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    ISSN: 1432-0789
    Keywords: Key words Methane ; Wetland rice soils ; Oryza sativa ; Methane oxidation ; Acetylene Propylene oxide ; Methanotrophs ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Acetylene up to 500 μl l–1 did not affect methane formation in anoxic soil up to 12 h, but further incubation for 1 week showed strong inhibition of methanogenesis. To ascertain the extent of the oxidation of methane produced from rice-planted pots, the effect of acetylene on methane emission was studied. Two rice varieties (Toyohatamochi and Yamahikari) were grown in a greenhouse in submerged soil in pots. At about maximum tillering, heading, and grain-forming stages, methane fluxes were measured. Flux measurement was performed for 3 h from 6 pm, then acetylene at 100 μl l–1 was added to some of the pots. At 6 a.m. the following day, methane fluxes were again measured for 3 h. Only at maximum tillering stage of the variety Toyohatamochi was a significant increase (1.4 times) in methane flux caused by acetylene observed, whereas in the other treatments no significant increase in methane fluxes by acetylene could be defected. To ascertain the activity of methane monooxygenase (MMO), propylene oxide (PPO) formation from propylene was measured with excised roots and a basal portion of stems of the rice plants grown on the submerged soil. A level of 0.1–0.2 μmol PPO h–1 plant–1 was recorded. The roots showed the highest PPO formation per gram dry matter, followed by basal stems. Methane oxidation was roughly proportional to PPO formation. Soluble MMO-positive methanotroph populations were measured by plate counts. The number of colony-forming units per gram dry matter was 106–105 in roots, and 104–103 in basal stems. These results indicate the possibility of methane oxidation in association with wetland rice plants.
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    URL: http://dx.doi.org/10.1007/s003740050241
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    Using the spermosphere model technique to describe the dominant nitrogen-fixing microflora associated with wetland rice in two Egyptian soils (1989)
    Springer
    Biology and fertility of soils 7 (1989), S. 158-163 
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    ISSN: 1432-0789
    Keywords: Rhizosphere ; N2-fixation ; Wetland rice ; Dominant microflora ; Spermosphere model ; Enterobacter cloacae ; Enterobacter agglomerans ; Citrobacter freundii ; Klebsiella planticola ; Azospirillum lipoferum ; Azospirillum brasilense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study is an attempt to describe the dominant N2-fixing microflora associated with the roots of wetland rice. Rice cultivar Giza 171 was grown in a phytotron on two alluvial Egyptian soils for 8 days, a stage when the nitrogenase activity of undisturbed plants reached a level of 245 × 10−6 mol C2H4 h−1 g−1 dry weight of leaf. The roots and rhizosphere soils were then used for counting and isolating dominant diazotrophs. Counts and initial enrichment steps were carried out on a selective medium made of an axenic rice plantlet, the “spermosphere model”, incubated under 1 % acetylene. The counts were very high, exceeding 108 bacteria g−1 dry weight of rhizosphere soil. Enterobacteriaceae were dominant; most isolates were Enterobacter cloacae belonging to different biotypes in the two soils. Enterobacter agglomerans, Citrobacter freundii and Klebsiella planticola were also present as members of the dominant microflora. Azospirillum brasilense and Azospirillum lipoferum were present as well, but less abundant.
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    Nitrification of ammonium in different components of a flooded rice soil system (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 321-326 
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    ISSN: 1432-0789
    Keywords: Key words Nitrification ; Flooded rice soils ; Rhizosphere ; Rice variety ; Crop growth stage ; Organic amendment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrification associated with the various components [subsurface soil from unplanted and planted (rhizosphere) fields, standing water and surface soil from planted and unplanted fields and leaf sheath suspensions] of submerged rice paddies was examined in incubation experiments with solutions inoculated with soil or water samples. Substantial nitrification occurred in all samples, standing water and surface soil samples in particular, during their 40-day incubation with NH4 +-N. Almost all the NH4 +-N, disappeared during incubation with standing water, was recovered as NO3 –-N. This, compared to 70–80% from all soil samples and only 29% from leaf sheath suspensions. Significant loss of nitrogen, especially from leaf sheath suspensions, is probably due to nitrification-denitrification as evidenced by its complete recovery in the presence of N-Serve. Nitrification potential of the soil and water samples varied with the crop growth stage and was more pronounced at tillering and panicle inititation stages than at other stages. Nitrification potential of samples from green-manure-amended plots was distinctly less than that of samples from control and urea-amended plots. Most probable number (MPN) estimates of ammonium-oxidizing bacteria were always higher in surface soil in both planted and unplanted plots at all stages of crop growth.
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    Gram-negative bacterial flora on the root surface of wheat (Triticum aestivum) grown under different soil conditions (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 273-281 
    Details
    ISSN: 1432-0789
    Keywords: Wheat ; Triticum aestivum ; Rhizosphere ; Soil microflora ; Gram-negative bacteria ; API 20 NE ; Flavobacterium spp ; Cytophaga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We identified 161 Gram-negative bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into seven groups based on major morphological and physiological properties. Taxonomic allocation of the groups was verified by guanine+cytosine contents of DNA. Except for one group, which may be assumed to include bacteria belonging to the genera Flavobacterium and Cytophaga, the various groups were taxonomically united. The distribution of the groups changed with soil improvement. Pseudomonads predominated in unimproved soil, but Flavobacterium and Cytophaga spp. were predominant in the most improved soil. As all the strains were non-fermentative by Hugh and Leifson's test, API 20NE identification was applied. However, many strains were misidentified by this system, especially in the Flavobacterium and Cytophaga spp. group. For ecological studies, the strains were classified to species level by the API 20 NE system and by the results of a combination of guanine+cytosine (mol%) and isoprenoid quinone data. The pattern of distribution of the bacteria on the root surface of wheat varied at species level within one genus depending on soil conditions.
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    Antagonistic effect of Pseudomonas spp. on pathogenic fungi and enhancement of growth of green gram (Vigna radiata) (1999)
    Springer
    Biology and fertility of soils 29 (1999), S. 62-68 
    Details
    ISSN: 1432-0789
    Keywords: Key words Pseudomonas spp. ; Vigna radiata ; Rhizosphere ; Antifungal activity ; Dinitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pseudomonas species were isolated from the rhizosphere of green gram [Vigna radiata (L.) Wilczek] and some of the rhizobacterial isolates were found to have a wide range of antifungal activity inhibiting growth of the phytopathogenic fungi Aspergillus sp., Curvularia sp., Fusarium oxysporum and Rhizoctonia solani in culture. These isolates also showed slight inhibition of the growth of a Bradyrhizobium strain (Vigna) in a spot test which was mainly a result of nutrient competition as culture supernatants of the Pseudomonas isolates did not inhibit the growth of bradyrhizobia but inhibited the growth of fungi. The rhizobacterial isolates produced siderophores in Fe-deficient succinate medium. However, the inhibition of fungal growth by different Pseudomonas isolates in Luria Bertani and King's medium B which were not limiting in Fe3+ ions suggested that, besides siderophores, other antifungal compounds (antibiotics) produced by these rhizobacteria were involved in antagonism. On coinoculation of green gram with Pseudomonas strains MRS13 and MRS16 and Bradyrhizobium sp. (Vigna) strain S24, there was a significant increase in nodule weight, plant dry weight and total plant N as compared to inoculation with Bradyrhizobium strain S24 alone, suggesting that the nodule-promoting effects of Pseudomonas sp. lead to an increase in symbiotic N fixation and plant growth.
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    Effect of low pO2 on colonization of maize roots by a genetically altered Pseudomonas putida [PH6(L1019)] (1997)
    Springer
    Biology and fertility of soils 26 (1997), S. 43-49 
    Details
    ISSN: 1432-0789
    Keywords: Key words Low pO2 ; Rhizosphere ; Pseudomonads ; Competition ; LacZY
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Among the factors which may affect colonization of roots by soil bacteria is that of rhizosphere oxygen partial pressure (pO2). The oxygen concentration in the root zone influences both microbes and roots. Roots exposed to low pO2, as might occur during flooding and waterlogging of the soil, become more leaky and loss of soluble carbon increases. To determine whether periods of low pO2 increased root colonization by a genetically altered pseudomonad we inoculated 3- to 4-week-old maize plants, grown in soil and transferred to a hydroponic system or grown in fritted clay, with Pseudomonas putida PH6(L1019)(lacZY+) following exposure of the roots to air or cylinder N2. Numbers of heterotrophs and the marked pseudomonad were determined by dilution plating. Low pO2 generally increased the numbers of bacteria associated with roots exposed to the treatments in solution or in undisturbed fritted clay rooting medium. Under low pO2 in a hydroponic system, roots of intact maize plants tended also to have higher soluble organic C and hexose (anthrone-detectable sugars) than roots exposed to air. The effect of low pO2 was most pronounced in the fritted clay where low pO2 favored colonization by the marked strain; numbers were 3- to 96-fold greater than those on roots flushed with air but accounted for only 0.06–0.61% of the total population. Roots exposed to low pO2 tended to accumulate more C. Results suggest that in the fritted clay, the pseudomonad was able to exploit the increased C supply and to achieve greater numbers on roots exposed to low pO2, whereas the dilution of carbon released from roots in the hydroponic apparatus did not allow for the same magnitude of increase on roots.
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    Effects of marigold (Tagetes sp.) roots on soil microorganisms (1998)
    Springer
    Biology and fertility of soils 27 (1998), S. 149-154 
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    ISSN: 1432-0789
    Keywords: Key words Marigold ; Tagetes ; Rhizosphere ; Nematode suppression ; Bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Marigolds (genus Tagetes) suppress populations of soil endopathogenic nematodes such as Pratylenchus penetrans and Meloidogyne species. Nematode suppression by marigolds is thought to be due to thiophenes, heterocyclic sulfur-containing molecules abundant in this plant. When activated, thiophenes such as α-terthienyl produce oxygen radicals. If marigold roots release such a powerful biocidal agent and it is activated in soil, microbial populations in the marigold rhizosphere should be substantially perturbed. We made various measurements of microbial population size and activity in soils that had been cropped to marigolds (Crackerjack, Creole) in the field and in the greenhouse, and compared these with bare soil and soil cropped to rye (Secale cereale L.). Total extractable microbial biomass (measured by the fumigation extraction method), total bacteria (measured by epifluorescence microscopy on 5-(4,6-dichlorotriazine-2-γl) aminofluorescein-stained preparations), heterotrophic bacteria (measured by plate count on various media), and nitrite-oxidizing bacteria (measured by the most-probable-number method) were not significantly different in any of the treatments. Residues of 14C-labelled rye were mineralized slightly more rapidly in rye-cropped soil than in the other treatments, which were comparable. The rates of die-back of introduced cells of the bacteria Escherichia coli and Rhodococcus TE1 were similar in marigold-cropped and control soils, suggesting that there was not a noteworthy accumulation of biocidal agents in soils cropped to marigolds. We conclude that marigolds do not cause a general depression in the numbers of microorganisms in soils, and that nematode control by this plant may not be due to the release of a biocidal agent into the soil.
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    Survival and cell culturability of biocontrol Pseudomonas fluorescens CHA0 in the rhizosphere of cucumber grown in two soils of contrasting fertility status (2000)
    Springer
    Biology and fertility of soils 32 (2000), S. 217-221 
    Details
    ISSN: 1432-0789
    Keywords: Key words  Pseudomonas fluorescens ; Cucumber ; Rhizosphere ; Biocontrol ; Culturability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The effect of cucumber roots on survival patterns of the biocontrol soil inoculant Pseudomonas fluorescens CHA0-Rif was assessed for 22 days in two non-sterile soils, using a combination of total immunofluorescence cell counts, Kogure's direct viable counts and colony counts on plates containing rifampicin. In Eschikon soil (high fertility status for cucumber), CHA0-Rif persisted as culturable cells in bulk soil and in the rhizosphere, but colony counts were lower than viable counts and total cell counts inside root tissues. The occurrence of viable but non-culturable (VBNC) cells inside root tissues (5 log cells g–1 root) was unlikely to have resulted from the hydrogen peroxide treatment used to disinfect the root surface, as hydrogen peroxide caused the death of CHA0-Rif cells in vitro. In Siglistorf soil (low fertility status for cucumber), the inoculant was found mostly as non-culturable cells. Colony counts and viable counts of CHA0-Rif were similar, both in bulk soil and inside root tissues, whereas in the rhizosphere viable counts exceeded colony counts at the last two samplings (giving about 7 log VBNC cells g–1). In conclusion, soil type had a significant influence on the occurrence of VBNC cells of CHA0-Rif, although these cells were found in root-associated habitats (i.e. rhizosphere and root tissues) and not in bulk soil.
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    Misidentification of soil bacteria by fatty acid methyl ester (FAME) and BIOLOG analyses (2000)
    Springer
    Biology and fertility of soils 32 (2000), S. 256-258 
    Details
    ISSN: 1432-0789
    Keywords: Key words Arthrobacter ; Micrococcus ; Rhizosphere ; Similarity index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Fatty acid methyl ester (FAME) analysis is commonly used by soil scientists as a sole method for identifying soil bacteria. We observed discrepancies with this method for identifying certain species of bacteria. Therefore, we used carbon substrate oxidation patterns (BIOLOG) and some simple physical and chemical tests to determine the extent of these discrepancies. Identification with FAME profiles gave false positives for Arthrobacter globiformis, Micrococcus kristinae, and M. luteus, and identification with BIOLOG patterns gave a false positive identification for A. globiformis. A visual check and Gram stain are recommended when FAME analysis identifies soil isolates as M. kristinae or M. luteus, and an additional spore formation test is recommended when FAME and BIOLOG analyses identify isolates as A. globiformis.
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    Production of root-derived material and associated microbial growth in soil at different nutrient levels (1987)
    Springer
    Biology and fertility of soils 5 (1987), S. 126-132 
    Details
    ISSN: 1432-0789
    Keywords: Residual soil 14C ; Microbial biomass ; Root-derived organic matter ; Fluorescent pseudomonads ; Rhizosphere ; Nutrient levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Maize plants were grown for 42 days in a sandy soil at two different mineral nutrient levels, in an atmosphere containing 14CO2. The 14C and total carbon contents of shoots, roots, soil and soil microbial biomass were measured 28, 35 and 42 days after germination. Relative growth rates of shoots and roots decreased after 35 days at the lower nutrient level, but were relatively constant at the higher nutrient level. In the former treatment, 2% of the total 14C fixed was retained as a residue in soil at all harvests while at the higher nutrient level up to 4% was retained after 42 days. Incorporation of 14C into the soil microbial biomass was close to its maximum after 35 days at the lower nutrient level, but continued to increase at the higher level. Generally a good agreement existed between microbial biomass, 14C contents and numbers of fluorescent pseudomonads in the rhizosphere. Numbers of fluorescent pseudomonads in the rhizosphere were maximal after 35 days at the lower nutrient level and continued to increase at the higher nutrient level. The proportions of the residual 14C in soil, incorporated in the soil microbial biomass, were 28% to 41% at the lower nutrient level and 20%6 – 30% at the higher nutrient level. From the lower nutrient soil 18%6 – 52%6 of the residual soil 14C could be extracted with 0.5 N K2SO4, versus 14%6 – 16% from the higher nutrient soil. Microbial growth in the rhizosphere seemed directly affected by the depletion of mineral nutrients while plant growth and the related production of root-derived materials continued.
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    A sensitive method for measuring cyanide and cyanogenic glucosides in sand culture and soil (1987)
    Springer
    Biology and fertility of soils 5 (1987), S. 141-147 
    Details
    ISSN: 1432-0789
    Keywords: Cyanogenic glucosides ; Cyanide ; Root exudates ; Rhizosphere ; Linum usitatissimum ; Pteridium aquilinum ; Linamarase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sensitive methods for measuring cyanide and cyanogenic glucosides in soil and sand culture have been developed. A microdiffusion technique is described which depends on the enzymic conversion of linamarin and lotaustralin to HCN, its release following acidification and incubation, and its detection in NaOH. Conditions for hydrolysis and HCN recovery have been optimised. The cyanide content of a silt loam soil (under non-cyanogenic wheat) was 5.47 nmol cyanide g−1 air-dried soil whilst that in an organic soil under the cyanogenic bracken, Pteridium aqgilinum, was 12.2 nmol g−1. Exudation of cyanogenic glucosides by linseed, Linum usitatissimum, was measured in plant growth tubes containing sand and a nutrient medium. Sterile plants exuded an average of 6.88 nmol glucosides plant−1 week−1 whilst, in contaminated tubes, the level fell to 4.72 nmol. Analysis of plant roots on each sampling occasion showed that 6.88 nmol was, on average, equivalent to 16.15% of the total root content of cyanogenic glucosides. There was a low but positive correlation between fresh weight of plant roots and the level of exuded glucosides. There was no evidence that plant roots produced free HCN.
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    Root activity and carbon metabolism in soils (1988)
    Springer
    Biology and fertility of soils 7 (1988), S. 71-78 
    Details
    ISSN: 1432-0789
    Keywords: Root activity ; Rhizosphere ; C metabolism ; Microbial biomass ; Microbial activity ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two different soils were amended with 14C-labelled plant material and incubated under controlled laboratory conditions for 2 years. Half the samples were cropped with wheat (Triticum aestivum) 10 times in succession. At flowering, the wheat was harvested and the old roots removed from the soil, so that the soil was continuously occupied by predominantly active root systems. The remaining samples were maintained without plants under the same conditions. During the initial stages of high microbial activity, due to decomposition of the labile compounds, the size of the total microbial biomass was comparable for both treatments, and the metabolic quotient (qCO2-C = mg CO2-C·mg−1 Biomass C·h−1) was increased by the plants. During the subsequent low-activity decomposition stages, after the labile compounds had been progressively mineralized, the biomass was multiplied by a factor of 2–4 in the presence of plants compared to the bare soils. Nevertheless, qCO2-C tended to reach similar low values with both treatments. The 14C-labelled biomass was reduced by the presence of roots and qCO2-14C was increased. The significance of these results obtained from a model experiment is discussed in terms of (1) the variation in the substrate originating from the roots and controlled by the plant physiology, (2) nutrient availability for plants and microorganisms, (3) soil biotic capacities and (4) increased microbial turnover rates induced by the roots.
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    Inoculation of rice with nitrogen-fixing bacteria —problems and perspectives (1987)
    Springer
    Biology and fertility of soils 4 (1987), S. 21-26 
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    ISSN: 1432-0789
    Keywords: Bacterial inoculation ; Rice yield ; Associative nitrogen fixation ; Azotobacter spp. ; Azospirillum spp. ; Pseudomonas spp. ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The present status and merits of inoculating rice with N2-fixing bacteria are discussed in the light of recent advances. Bacterial inoculation improves plant growth and rice yield but not uniformly. The yield response to inoculation is more pronounced in the presence of moderate levels of fertilizer N. Evidence for the establishment and activity of the inoculated bacteria is limited, and the poor survival of the inoculum under field conditions further complicates the effects of inoculation. There is no clear evidence that improved growth and mineral content following inoculation are due to increased N2 fixation. Beneficial effects of the inoculum on rice, such as plant growth promotion, N2 fixation and antagonism effects against pathogens need to be further investigated under laboratory and field conditions. Improved management practices, such as organic amendments, suitable water and soil management, selection of efficient microbial strains, selection of effective breeding lines with high associative nitrogen fixation, and better management of agrochemicals are some of the measures suggested for deriving benefits from bacterial associations with rice.
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    URL: http://dx.doi.org/10.1007/BF00280346
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    Organic and inorganic soil phosphates and acid phosphatase activity in the rhizosphere of 80-year-old Norway spruce [Picea abies (L.) Karst.] trees (1989)
    Springer
    Biology and fertility of soils 8 (1989), S. 128-133 
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    ISSN: 1432-0789
    Keywords: Organic phosphates ; Rhizosphere ; Mycorrhizal roots ; Acid phosphatase ; Picea abies (L.) Karst. ; Norway spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Inorganic and organic phosphates (P) were measured in bulk soil, rhizosphere soil and mycorrhizal rhizoplane soil of Norway spruce. Various methods of P extraction and estimation were compared. In addition, acid phosphatase activity and mycelial hyphae length were determined. In soil solutions from various locations, about 50% (range 35%–65%) of the total P was present as organic P. Compared to the bulk soil, the concentrations of readily hydrolysable organic P were lower in the rhizosphere soil and in the rhizoplane soil; this difference was particularly marked in the humus layer. In contrast, the concentrations of inorganic P either remained unaffected or increased. A 2- to 2.5-fold increase was found in the activity of acid phosphatase in the rhizoplane soil in comparison to the bulk soil. There was a positive correlation (r = 0.83***) between phosphatase activity and the length of mycelial hyphae. The results stress the role of organic P and of acid phosphatase in the rhizosphere in the P uptake by mycorrhizal roots of spruce trees grown on acid soils.
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    URL: http://dx.doi.org/10.1007/BF00257756
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    Cellulolytic and pectolytic activity of streptomycetes isolated from root-free soil, rhizosphere and mycorrhizosphere of pine (Pinus sylvestris L.) (1989)
    Springer
    Biology and fertility of soils 7 (1989), S. 365-369 
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    ISSN: 1432-0789
    Keywords: Streptomycetes ; Cellulolytic ; Pectolytic activity ; Pine ; Pinus sylvestris ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Our studies have revealed that streptomycetes inhabiting root-free soil and the root zone of pine trees differ in their capacity to produce cellulolytic and pectolytic enzymes. Most of the root-zone organisms but only a few of the root-free soil isolates exhibited cellulolytic activity. A few of the root-zone organisms but no soil isolate showed pectolytic activity. In general the cellulolytic activity was higher in cellulase producers from the root zone than in those derived from the root-free soil. The streptomycetes studied produced only endopolymethylgalacturonase. The mean total activity of this enzyme was higher in the rhizosphere isolates but the mean specific activity was higher in the mycorrhizosphere organisms.
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    URL: http://dx.doi.org/10.1007/BF00257834
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    The Platanar-Aguas Zarcas volcanic centers, Costa Rica: spatial-temporal association of Quaternary calc-alkaline and alkaline volcanism (1993)
    Springer
    Bulletin of volcanology 55 (1993), S. 443-453 
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    ISSN: 1432-0819
    Keywords: Arc volcano ; magma mixing ; geochemistry ; alkaline ; calc-alkaline ; sector collapse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Platanar volcanic center is dominated by a calc-alkaline, basalt-andesite-dacite-rhyolite magma series with unusual LREE enrichment. Adjacent and overlapping the calc-alkaline rocks are the most alkaline basalts found along the volcanic front of Central America. These basalts are mafic, LIL- and LREE-enriched transitional to alkaline basalts. Several are found on the north flank of Platanar in the Aguas Zarcas region, where there are nine cinder cones and a few isolated flows. However, they are also found in isolated lava outcrops at least as far south as Porvenir volcano along the volcanic front. The addition of mafic alkaline magmas with high La/Yb and low Ba/La into the Platanar magma chamber or chambers may contribute to the LREE-enriched character of the Platanar basaltic andesites and andesites. At Platanar the field and geochemical evidence suggest mixing between calc-alkaline and alkaline magmas, a process that has probably occurred throughout the development of the Cordillera Central of Costa Rica. The presence of negative Ce anomalies in several of the calc-alkaline lavas also make the Platanar complex very unusual compared to the rest of the Central American volcanic front. In the center of the Platanar complex is the Chocosuela caldera, an apparent remnant of an avalanche caldera created by the collapse in the Middle Pleistocene of an ancestral stratovolcano toward the NNW in a directed blast-type eruption. Rhyolite is present as pumice lapilli in pyroclastic flow deposits outside the caldera rim. Whole lapilli analyses span the daciterhyolite range. The previous eruption of high silica tephra as pyroclastic flows, the current long dormant period and the repeated occurrence of earthquake swarms on the flanks of the Platanar complex make it a candidate for volcanic hazard mapping, detailed geological mapping and emergency planning.
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    A multi-proxy study of Holocene environmental change in the Maya Lowlands of Peten, Guatemala (1998)
    Springer
    Journal of paleolimnology 19 (1998), S. 139-159 
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    ISSN: 1573-0417
    Keywords: geochemistry ; Guatemala ; Holocene ; lakesediment ; Maya ; magnetic susceptibility ; paleolimnology ; pollen ; stable isotopes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We used multiple variables in a sediment core from Lake Peten-Itza, Peten, Guatemala, to infer Holocene climate change and human influence on the regional environment. Multiple proxies including pollen, stable isotope geochemistry, elemental composition, and magnetic susceptibility in samples from the same core allow differentiation of natural versus anthropogenic environmental changes. Core chronology is based on AMS 14C measurement of terrestrial wood and charcoal and thus avoids the vagaries of hard-water-lake error. During the earliest Holocene, prior to ∼9000 14C yr BP, the coring site was not covered by water and all proxies suggest that climatic conditions were relatively dry. Water covered the coring site by ∼9000 14C yr BP, coinciding with filling of other lakes in Peten and farther north on the Yucatan Peninsula. During the early Holocene (∼9000 to ∼6800 14C yr BP), pollen data suggest moist conditions, but high δ 18O values are indicative of relatively high E/P. This apparent discrepancy may be due to a greater fractional loss of the lake's water budget to evaporation during the early stages of lake filling. Nonetheless, conditions were moist enough to support semi-deciduous lowland forest. Decrease in δ 18O values and associated change in ostracod species at ∼6800 14C yr BP suggest a transition to even moister conditions. Decline in lowland forest taxa beginning ∼5780 14C yr BP may indicate early human disturbance. By ∼2800 14C yr BP, Maya impact on the environment is documented by accelerated forest clearance and associated soil erosion. Multiple proxies indicate forest recovery and soil stabilization beginning ∼1100 to 1000 14C yr BP, following the collapse of Classic Maya civilization.
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    URL: http://dx.doi.org/10.1023/A:1007968508262
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    Holocene sedimentation in Lake Winnipeg, Manitoba, Canada: implications of compositional and textural variations (1998)
    Springer
    Journal of paleolimnology 19 (1998), S. 265-284 
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    ISSN: 1573-0417
    Keywords: Holocene ; lacustrine ; sedimentation ; Lake Winnipeg ; sediment cores ; geochemistry ; mineralogy ; texture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Two seismic facies were recognized in the sedimentary sequence overlying acoustic basement in Lake Winnipeg. The upper facies, which overlies a regional unconformity, is termed the Lake Winnipeg Sequence. Based on the seismostratigraphy, lithostratigraphy, and radiocarbon dates of approximately 4000 and 7000 yr BP from material collected directly over the unconformity in the southern and northern parts of the lake, respectively, this facies has been interpreted as representing Holocene sedimentation. Results of compositional and textural analyses of the Holocene sediment (Winnipeg sediment) from thirteen long (〉2 m) cores indicate a transgressional sequence throughout the basin. In the South Basin, the generally fining upward sequence is characterized at the base by silt-sized detrital carbonate minerals, quartz and feldspar which decrease in concentration upward. In this basin, the high carbonate content and V/Al and Zn/Al ratios are indicative of a Paleozoic and Cretaceous provenance for sediment derived from glacial deposits through shoreline erosion and fluvial transport, via the Red River. Sedimentation in the central part of the lake and the North Basin is attributed to shoreline erosion of sand and gravel beaches. Consequently, the texture of these sediments is generally coarser than in the South Basin, and the composition primarily reflects a Paleozoic and Precambrian provenance. The basin-wide decrease in Ca, total carbonate minerals, dolomite and calcite concentrations upward in the cores is reflected by a decrease in the detrital carbonate component in all but the most northern cores. Other basin-wide trends show an upward increase in organic content in all cores. An increase in grain size near the top of most cores suggests a major, basin-wide change in sedimentation within the last, approximately 900 years in the South Basin.
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    Sediment heavy metal record in Lake Baikal: natural and antrhopogenic sources (1998)
    Springer
    Journal of paleolimnology 20 (1998), S. 135-150 
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    ISSN: 1573-0417
    Keywords: geochemistry ; heavy metals ; lake sediments ; palaeolimnology ; Lake Baikal ; Russia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Geochemical analysis of six radiometrically dated short cores of recent sediment from Lake Baikal shows clear evidence of enhanced Pb supply. However, the sediment concentration increases are very small; the average Pb concentration rises from a baseline value of 10.9 μg g-1 to a peak value of only 14.8 μg g-1. In contrast to the more polluted lakes commonly studied in Europe and North America, variation in Pb concentration is far more strongly influenced by natural variation than by pollution. In sediment deposited over the last 150–200 years 73% of the variance in the sediment Pb concentration can be accounted for by variation in bulk composition of the sediment, and by atmospheric pollution. Factors influencing Pb concentrations over this time period are, in order of decreasing average importance (fraction of total variance explained), catchment supply (indicated by 226Ra activity variation) (43%), anthropogenic Pb emissions (24%), and dilution by ferromanganese hydroxides (6%). On longer (1000s of years) time scales dilution by biogenic silica is probably more important. The recent enhanced supply of catchment Pb correlates with accelerating accumulation rates, indicating a link with enhanced erosion. Anthropogenic sources dominate only in the southern basin, where local fossil-fuel burning industry is situated. The evidence for a local industrial source for the Pb pollution is strengthened by the high correlation between the inventories for Pb and for spheroidal carbonaceous particles. The absence of detectable anthropogenic Pb enrichment in the northern part of the lake suggests that long-distance Pb pollution is small compared with the local natural supply.
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    Stratigraphy of total metals in PIRLA sediment cores (1992)
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    Journal of paleolimnology 7 (1992), S. 191-214 
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    ISSN: 1573-0417
    Keywords: geochemistry ; metals ; lake sediments ; paleolimnology ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from 30 low-alkalinity lakes in northern New England (NE), New York (NY), the northern Great Lakes States (NGLS) of Minnesota, Michigan, and Wisconsin, and Florida (FL) have been dated by 210Pb and analyzed for water and organic content, eight major elements (Al, Ti, Fe, Mn, Ca, Mg, Na, K) plus four trace metals (Pb, Zn, Cu, and V). Variations in the percentages of major elements through time are dominated by long-term independent variations in the abundance of SiO2, FeO, and to a lesser extent Ca and Al. Additional variations are caused by varying proportions of inorganic matter. Major variations in chemistry are generally unrelated to documented distrubances in the watersheds; most disturbances are minor fires or selective logging. Accelerated accumulation of Pb from atmospheric sources into sediment first occurs in sediment dated between 1800 and 1850 in NY and NE, slightly later in the NGLS region, and about 1900 in FL. Modern accumulation rates in all areas are comparable (ca. 1 to 4 μg cm−2 yr−1). Accumulation rates of Pb in some lakes have declined significantly from 1975 to 1985. Atmospheric deposition of anthropogenic Zn and Cu is also indicated by generally increasing accumulation rates in sediment cores, but the record is not as clear nor are chemical profiles in all lakes parallel to the trends in atmospheric emissions inferred on the basis of fossil fuel consumption, smelting, and other industrial activities. Inter-lake variations in profiles of Cu and Zn are large. Vanadium accumulation rates increase by the 1940s in NY and NE, but not until the 1950s in the NGLS region. This timing correlates with regional trends in the combustion of fuel oil, a major source of atmospheric V. Acidification of some of the lakes is suggested by decreases in the concentration and accumulation rates of Mn, Ca, and Zn in recent sediment, relative to other elements of catchment origin. The decreases generally occur slightly before the onset of acidification as indicated by diatoms. Increased sediment accumulation rates for Fe may indicate the acidification of watershed soils. The use of the accumulation rate of TiO2 as an indicator of rates of erosion and for normalization of trace metal accumulation rates is in question for lakes where the flux of TiO2 from the atmosphere varies and is a significant fraction of the total flux of TiO2 to the sediment.
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    Paleoecological investigation of recent lake acidification in the northern Great Lakes states (1990)
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    Journal of paleolimnology 4 (1990), S. 153-201 
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    ISSN: 1573-0417
    Keywords: lake acidification ; mid-western U.S.A. ; diatoms ; geochemistry ; pollen ; land use
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Paleoecological analyses of sediments from nine northern Great Lakes states (NGLS) lakes reveal small pH changes in seven of these lakes since 1860, four of these being declines. The largest diatom-inferred (DI) pH declines of 0.5 pH units were found in Brown L. and Denton L., Wisconsin. Two other lakes with suspected total alkalinity declines (based on an acidification model and on historical water chemistry, respectively), McNearney L., Michigan, and Camp 12 L., Wisconsin, have not acidified recently according to diatom-inference techniques. Many of the observed trends of increasing pH are coincident with logging; floristic composition of diatom assemblages also changed coincident with fisheries manipulations in some lakes, but these floristic trends did not affect DI pH. Sediment core profiles of Pb, S, and polycyclic aromatic hydrocarbons provide a record of atmospheric deposition of fossil fuel combustion products beginning around the turn of the century; onset is later and accumulation rates are smaller than for other northeastern study regions of the Paleoecological Investigation of Recent Lake Acidification (PIRLA) Project. The response of diatom species to lakewater pH in the NGLS region is very strong and similar to response in other regions. Overall, there is little paleoecological evidence that acidic deposition has caused significant acidification of lakes in the NGLS region.
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    Paleochemistry and paleohydrology of Ceylon Lake, a salt-dominated playa basin in the northern Great Plains, Canada (1990)
    Springer
    Journal of paleolimnology 4 (1990), S. 219-238 
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    ISSN: 1573-0417
    Keywords: saline lakes ; geochemistry ; paleohydrology ; paleoclimate ; Saskatchewan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract In the western part of the Canadian Prairies, there are thousands of small, closed-basin saline lakes. Most of these lakes are ephemeral, filling with water during the spring and drying completely by late summer. Ceylon Lake, located in southern Saskatchewan, is typical of many of these shallow ephemeral lacustrine basins. The stratigraphic sequence recovered from this salt playa can be subdivided into six distinct facies types: (a) icelaid gravelly clay loam diamicton; (b) fluvial massive bedded to laminated sand; (c) lacustrine laminated calcareous clay and silt; (d) lacustrine laminated gypsiferous clay and silt; (e) lacustrine black, anoxic, nonlaminated, organic-rich mud; and (f) lacustrine salt. The crystalline salt facies, which can be up to 9 meters thick, is comprised mainly of sodium and sodium + magnesium sulfates, with smaller and more variable proportions of other sulfates, halides, carbonates, and insoluble clastic detritus. Although a variety of postdepositional processes have significantly altered the nature and stratigraphic relationships in the basin, the sediment fill does record, in a general way, the fluctuating depositional, hydrological, and geochemical conditions that existed in the basin since deglaciation. The Ceylon Lake basin originated about 15 000 years ago as meltwater from the retreating glacial ice cut a major spillway system in the drift and bedrock. The initial (early Holocene) phases of lacustrine sedimentation in Ceylon Lake occurred in a relatively deep freshwater lake. By about 6000 years B.P., the lake had become much shallower with numerous episodes of complete drying and subaerial exposure. The most recent 5000 years of deposition in the basin have been dominated by evaporite sedimentation. The composition of the soluble salts deposited during this time indicates some degree of cyclic sedimentation superimposed on an overall gradual shift from a sodium dominated brine to one of mixed sodium and magnesium.
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    Catchment disturbance inferred from paleolimnological studies of three contrasted sub-humid environments in Morocco (1988)
    Springer
    Journal of paleolimnology 1 (1988), S. 293-322 
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    ISSN: 1573-0417
    Keywords: catchment disturbance ; sediment cores ; magnetic minerals ; geochemistry ; pollen ; diatoms ; Morocco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Paleolimnological techniques for assessing recent drainage basin disturbance are evaluated in three Moroccan lakes with catchments contrasted in terms of land-use and vegetation. Rates of sediment accumulation in the two lakes with agricultural catchments were relatively high (〉1.6 cm yr-1) in the most recent past. Dilution effects prevented core dating by the 210Pb method alone and post-1953 chronologies were constructed by combining 210Pb and 137Cs data. The recent sediment accumulation rate at the currently least disturbed site, where natural Cedrus forest is still abundant, was relatively low (〈0.4 cm yr-1) but has increased since the mid-19th century. Magnetic, geochemical, pollen, and diatom studies of all three lake sediment cores linked with modern field survey data show that soil erosion in the most vegetationally disturbed catchment (Dayat-er-Roumi) has been high throughout the recent past and that intensity peaks are probably associated with wetland drainage operations beginning in the 1940's. At the partially forested site (Dayat Affougah), pre-1950's woodland clearance and other land-use changes are the likely cause of past major soil erosion episodes. The site currently dominated by natural Cedrus forest (Lac Azigza) shows only minor disturbance during the past c. 150 years although a major soil erosion episode occrred in the 17th century. Paleolimnological analysis has clearly demonstrated that major landscape change has occurred at all three sites. However, only at the two sites with catchment cultivation do previously accelerated soil erosion and lake sediment accumulation rates persist to the present. Information essential for formulation of appropriate management plans is presented and the importance of paleolimnology in assessing man-induced lake-catchment disturbance is stressed.
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    Early-Holocene geochemical evolution of saline Medicine Lake, South Dakota (1994)
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    Journal of paleolimnology 10 (1994), S. 69-84 
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    ISSN: 1573-0417
    Keywords: geochemistry ; salinity ; paleoclimate ; meromixis ; South Dakota
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Medicine Lake is a highly saline, meromictic, magnesium sulfate, closed-basin lake in northeastern South Dakota. The geochemical, mineralogical, and magnetic stratigraphies of sediments deposited from about 10.8 to 4.5 ka B.P. document the evolution of the saline brine in response to climatic change in the early to mid-Holocene. During the spruce occupation of the Medicine Lake catchment (10.8–10.0 ka B.P.), dark-grey massive basal sediments with low total-sulfur and carbonate content, upwardly increasing organic-carbon content, and high magnetic susceptibility were deposited in a deep freshwater lake. As the vegetation in the area changed from spruce to birch to oak and elm and finally to prairie between 10.0 and 9.2 ka B.P., and as the lake became shallow and salinity increased from 〈2 to 〉10%, light-and dark-grey calcareous and organic-carbon-rich banded sediments with low total-sulfur content and low magnetic susceptibility were deposited. Previous studies have shown that during the forest/prairie transition the lake then changed abruptly from fresh to saline as it lost a substantial portion of its volume. During the early prairie period (9.2–5.5 ka B.P.), alternating sections of aragonite-rich laminae and grey massive sediments with high total-sulfur content and multiple gypsum layers were deposited in a meromictic environment under conditions of fluctuating lake levels and salinity. Continued aridity during the mid-Holocene (5.5–4.5 ka B.P.) probably maintained the lake at relatively low levels and high salinity as dark-grey generally massive sediments with moderate total-sulfur, carbonate, and organic-carbon content and no measurable magnetic susceptibility were deposited.
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    A multi-proxy trophic state reconstruction for shallow Orange Lake, Florida, USA: possible influence of macrophytes on limnetic nutrient concentrations (1999)
    Springer
    Journal of paleolimnology 21 (1999), S. 215-233 
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    ISSN: 1573-0417
    Keywords: Florida ; geochemistry ; 210Pb dating ; macrophytes ; nutrients ; paleolimnology ; sediments ; shallow lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We retrieved four sediment cores from shallow, eutrophic, macrophyte-dominated Orange Lake (A = 51.4 km2, zmax 〈5 m, zmean 〈 2 m), north-central Florida, USA. The 210Pb-dated profiles were used to evaluate spatial and temporal patterns of bulk sediment and nutrient accumulation in the limnetic zone and to infer historical changes in lake trophic state. Bulk density, organic matter, total carbon, total nitrogen, total phosphorus and non-apatite inorganic phosphorus (NAIP) concentrations displayed stratigraphic similarities among three of four cores, as did accumulation rates of bulk sediment, organic matter and nutrients. Accumulation rates were slower at the fourth site. Nutrients showed generally increasing rates of accumulation since the turn of the century. Percentages of periphytic diatom taxa increased progressively in the cores after ~ 1930. Diatom-inferred limnetic total P trends were similar among profiles. Eutrophic conditions were inferred for the period prior to the turn of the century. The lake was hypereutrophic in the early decades of the 1900s, but inferred limnetic total P values declined after ~ 1930. Declining inferred limnetic total P trends for the last 60--70 years were accompanied by concomitant increases in accumulation rates of total P and NAIP on the lake bottom. Several lines of evidence suggest that after ~ 1930, phosphorus entering Orange Lake was increasingly utilized by submersed macrophytes. Paleolimnological records from Orange Lake highlight the importance of using multiple sediment variables to infer past trophic state and suggest that aquatic macrophytes can play a role in regulating water-column nutrient concentrations in shallow, warm-temperate lakes.
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    Late Pleistocene and early Holocene ecological response of Lake El Trébol (Patagonia, Argentina) to environmental changes (1999)
    Springer
    Journal of paleolimnology 22 (1999), S. 137-148 
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    ISSN: 1573-0417
    Keywords: paleolimnology ; geochemistry ; chironomids ; Late glacial - Holocene transition ; Argentina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Stratigraphy of Lake El Trébol (41°S 71°W, 758 m a.s.l.) described from an 11 m long sediment core provided a continuous record of patecenvironmental changes occurred during the last 14,000 years in southern South America east of the Andes. Located in an ecotonal area within a strong humidity gradient, this lake offers a unique opportunity to develop paleolimnological studies. Using a geochemical approach that includes elemental analysis, bulk organic matter, major nutrients and pigments combined with chironomids and pollen analysis, three zones were identified in the sedimentary record of this take. The oldest one (between 680 and 1,100 cm) corresponds to the late Glacial period. During that time, clayish laminated sediments were formed in a proglacial environment. Low organic matter, biogenic silica and nitrogen contents and the absence of pigments, pollen and chironomids characterise this period. At the end of this period, ca. 14,000 yr BP, a sharp increase in phosphorus concentrations predates major changes in limnological parameters. The transition zone (between 560 and 680 cm) is related to major changes in the drainage system that started soon after ca. 14,000 yr BP and continued to ca. 10,500 yr BP. The chemical composition of the sediments was affected by an increase in physical weathering mechanisms almost coincident with the increase in the regional volcanic activity that produced suspended volcanic detritus. The increase of mainly coarser detritical components may indicate a reorganisation of the fluvial system by that time. Simultaneously, an increase in the productivity of the lake accompanied by a gradual replacement of open vegetation with Nothofagus, Poaceae and Ericaceae, by Nothofagusforest, was observed. In the last zone (between 0 and 560 cm) the productivity of Lake El Trébol achieves maximum values. The trends in geochemical and biological indicators observed at Lake El Trébol can be up to some extent, correlated to those registered in Lake Mascardi. The results support earlier paleoctimatic scenarios from southern South America.
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    Rapid elemental analysis of sediment samples by isotope source XRF (2000)
    Springer
    Journal of paleolimnology 23 (2000), S. 213-221 
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    ISSN: 1573-0417
    Keywords: geochemistry ; heavy metals ; palaeolimnology ; sediment ; soil ; X-ray fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Energy dispersive isotope-source X-ray fluorescence (XRF) analysers are little used in academic environmental research, in spite of being ideally suited to a number of tasks. In this paper an XRF method is tested by measuring a wide range of environmental materials of known elemental composition. Precision, accuracy and detection limits are presented. Using isotope-source X-ray fluorescence analysis, the total concentrations of Si, Ti, Ca, K, Fe, Mn, Cl, S, Nb, Ni, Pb, Rb, Sr, Zn and Zr can be determined in soils and sediments at a rate of 〉70 samples per day. The combination of speed and accuracy makes the technique ideal for three classes of application within environmental research. First, in sediments and soils that are highly heterogeneous, reliable characterisation is more dependent upon the number of samples measured than on measurement precision or accuracy. Under these circumstances the method is sufficiently accurate to be used alone. This is also the case where there is high and wide ranging contamination of sediment or soil by Pb and Zn. Second, major elements (Si, Ti, Fe, Ca, K and S) can be measured with sufficient accuracy in sediments and soils to aid the interpretation of other sediment chemical analyses. Third, the technique is ideal for the rapid screening of sediment or soil, allowing effective targeting of samples for more time consuming or expensive analyses. The XRF method presented here offers rapid, non-destructive total elemental analysis of sediments and soils that is sufficiently accurate to be useful in environmental research.
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    URL: http://dx.doi.org/10.1023/A:1008053503694
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    Use of paleolimnology to document the effect of lake shoreland development on water quality (2000)
    Springer
    Journal of paleolimnology 24 (2000), S. 369-393 
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    ISSN: 1573-0417
    Keywords: paleolimnology ; shoreland development ; geochemistry ; diatoms ; eutrophication ; Wisconsin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Four Wisconsin, USA lakes were examined with paleolimnological techniques to determine the effects of shoreland development on water quality. Geochemical parameters such as aluminum, iron, manganese, phosphorus, nitrogen, and carbon were used to document watershed inputs while redox sensitive elements provided information on changes in hypolimnetic oxygen levels. Changes in the diatom community were used to assess the impacts of development upon the lakes' trophic status as well as changes in the littoral community. We assessed the relative sensitivity of high vs. low ANC lakes. The initial shoreland development, late in the 19th or early in the 20th century, involved seasonal cabins and minimal disturbance of the shoreland. This development phase had minimal impact upon the lakes compared to that during the mid- and late-twentieth century. Increased levels of iron and aluminum indicated the highest input of sediment occurred during the construction phase of converting shoreland homes from seasonal to year-round usage. Phosphorus deposition increased moderately in the high alkalinity lakes but more so in the low alkalinity lakes. In the low alkalinity stratified lake, increased levels of iron and manganese in the last decade indicated more anoxia in the hypolimnion. Phosphorus levels have also increased during this time period most likely as a result of elevated phosphorus release from the sediments. In the high alkalinity lakes, as the nutrient levels increased, diatom production initially shifted from benthic taxa of the family Fragilariaceae to metalimnetic taxa and as nutrients increased further, epilimnetic species. In the low alkalinity lakes, prior to settlement the major site of diatom prodution was the open water. Coincidental with the early shoreland development was an increase of macrophyte density as indicated by the epiphytic diatom Achnanthidium minutissimum ((Kützing) Czarnecki (= Achnanthes minutissima Kützing). The water quality in the high alkalinity lakes showed some improvement following completion of the home construction phase, especially in the lake with lower development density. The low alkalinity lakes did not show improved water quality and appear more sensitive to shoreland development.
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    URL: http://dx.doi.org/10.1023/A:1008107706726
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    Lithostratigraphy and recent sedimentation history of Little Manitou Lake, Saskatchewan, Canada (1994)
    Springer
    Journal of paleolimnology 10 (1994), S. 199-212 
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    ISSN: 1573-0417
    Keywords: saline lake ; geochemistry ; mineralogy ; lithostratigraphy ; paleolimnology ; Great Plains ; evaporites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Little Manitou Lake is a topographically closed, hypersaline lake that occupies a long, linear glacial meltwater channel in the northern Great Plains of western Canada. Most of the modern and late Holocene sediment in the lake has been generated from within the basin itself, either by endogenic inorganic precipitation or by other authigenic processes. These endogenic and authigenic precipitates, composed of mainly very soluble sulfate salts and sparingly soluble carbonates, provide an explicit record of the past chemical and hydrological fluctuations that have occurred in the lake. Although detailed chronostratigraphy is incomplete, preliminary14C dating indicates an age of about 2000 years for the oldest sediment recovered from the basin. Five subsurface sedimentary facies are identified in offshore cores. From the base these are: (i) structureless, gray clay, (ii) gypsiferous mud, (iii) structureless, organic-rich mud, (iv) finely laminated aragonitic mud, and (v) Na and Mg sulfate salts. The lithostratigraphy and variation in the mineralogical composition of the sediment indicate that Little Manitou Lake experienced significant water level changes and compositional fluctuations during the past several millennia. The basal clays indicate a relatively deep, freshwater lake existed about 2000 years ago, but was soon followed by a period of low water/playa sedimentation and a negative hydrological budget in the basin. Water levels gradually increased after about 1500 years ago in response to a cooler and wetter climate. This resulted in development of a meromictic, saline to hypersaline lake characterized by periodic carbonate (aragonite) whitings. Water levels again decreased about 1000 years ago, resulting in a breakdown of meromixis and initiation of subaqueous evaporitic salt precipitation. Although the brine in Little Manitou Lake has fluctuated between Na-SO4 and Mg-Na-SO4 -Cl types during the past 1000 years, water levels and overall salinities have remained relatively constant.
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    URL: http://dx.doi.org/10.1007/BF00684033
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    Recent environmental changes in a naturally acidic rocky lake in southern Finland, as reflected in its sediment geochemistry and biostratigraphy (1997)
    Springer
    Journal of paleolimnology 17 (1997), S. 191-213 
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    ISSN: 1573-0417
    Keywords: acidification ; geochemistry ; atmospheric loading ; diatoms ; in situ alkalinity ; forest fires
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Paleolimnological methods are combined with statistical multivariate analyses (PCA and CCA) to study the effects of local environmental disturbances and changes in loading of atmospheric origin on water acidity and the physiochemical properties of the sediment in a small, naturally acidic rocky lake in southern Finland. The pH of the lake as calculated from the diatom flora increased by 0.9 pH units as a consequence of a forest fire in the catchment area at the turn of the last century, and the changes in the diatom assemblages point to an increase in dys(eu)trophy and turbulence. In terms of element influx (in µg cm-2 yr-1), the effects of the fire are seen in a slight increase in the accumulation of lithophilous elements. Diatom-inferred pH values decline upwards in the sediment, but do not regain the level recorded before the fire. This is attributed to reactions between Fe3+ and S, which has partly accumulated from the air as SO2-, producing internal alkalinity. Accumulation rates of many elements increase markedly after the 1960s, an effect for Al, Mg, Na, P and Zn may be connected mainly with the enhanced accumulation of dry matter, whereas the accumulation of K, Ni, Pb, Ti and V in surface sediment are obviously related to atmospheric loading. Measured accumulation rates of Cd and Cu are lower than the calculated values especially in the surface sediment, possibly because of diagenetic changes. Accumulation of Ca and Mn decreases towards the surface on account of acidification of anthropogenic origin.
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    URL: http://dx.doi.org/10.1023/A:1007919922330
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    Diatom, pollen, and geochemical evidence for the palaeosalinity of Medicine Lake, S. Dakota, during the late-Wisconsin and early Holocene (1989)
    Springer
    Journal of paleolimnology 2 (1989), S. 159-172 
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    ISSN: 1573-0417
    Keywords: diatoms ; pollen ; geochemistry ; salinity ; paleoclimate ; South Dakota
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Medicine Lake is a highly saline meromictic lake in eastern South Dakota. A lithostratigraphic and biostratigraphic study of the late-glacial and early post-glacial sediments shows that it was a relatively deep dilute freshwater lake during the period of the Picea pollen zone. When spruce forest changed to a Betula and then to a Quercus/Ulmus woodland in the early post-glacial period, the lake water became more concentrated but remained fresh. However, during the subsequent rapid transition to prairie in the early Holocene, when Gramineae, Ambrosia, and Artemisia dominated dry-land vegetation, the freshwater diatom flora was progressively replaced by a saline assemblage characterized by Cyclotella quillensis, Chaetoceros, and eventually Cyclotella caspia. The lake became permanently saline at about 9000 yr BP. A comparison of the fossil diatom assemblages with surface-sediment samples from a range of lakes in the Dakotas indicates that the change involved an increase in conductivity from about 500 μS cm−1 in the late-glacial period to 〉 10 000 μS cm−1 in the early Holocene. This rapid change is also marked by an abrupt increase in sulphate concentration in the sediment, the first appearance of bands of gypsum crystals, and the beginning of a well-laminated core sequence that continues through the remaining sediment record. Conditions of high salinity have prevailed to the present day.
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    Effect of active roots on the decomposition of soil organic materials (1990)
    Springer
    Biology and fertility of soils 10 (1990), S. 121-126 
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    ISSN: 1432-0789
    Keywords: Biodegradation ; Nutrient levels ; Mineralization ; Rhizosphere ; Microenvironment ; Root exudates ; Priming effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of one form of soil organic matter, such as living roots or root exudates on another form of soil organic matter, such as dead roots or incorporated litter and litter leachates, has been studied from various perspectives over the last 25 years. The effect seems to be either positive (priming) or negative (conserving). The present review concentrates on the conserving effect, measured as a decrease in 14CO2 released, in both field and greenhouse/growth chamber studies. The field experiments suggested that certain physical conditions in the soil, such as less available moisture or restricted aeration which led to lower microbial activity, explained the conserving effect of living roots on soil organic matter. Although more detailed greenhouse/growth chamber studies confirmed the conserving effect per se, it appears that biological rather than physical factors could better explain the reduction in the rate of decomposition of 14C-labelled plant residues in the presence of roots. However, a complex picture has emerged through a variety of postulates, all proposed in attempts to explain the conserving effect. Finally, the most recent studies have argued that the decrease in decomposition of labelled organic matter in planted soil is probably more apparent than real. A decrease in respired 14CO2 could be explained by an incorporation of 14C derived from old roots into the rhizosphere microbial populations of the living roots. To make any further progress on the fundamental question of how soil organic matter moves along its continuum from a living to a refractory state, the microenvironment needs to be examined at periodic intervals. New developments in improved histochemical and electron-probe microanalyses look promising.
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    Effect of phosphonate on the rhizosphere microflora and the development of root rot (Phytophthora cinnamomi) in avocado (Persea americana) and pepper-corn (Schinus molle) tree seedlings (1991)
    Springer
    Biology and fertility of soils 11 (1991), S. 13-17 
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    ISSN: 1432-0789
    Keywords: Phosphonate ; Soil microorganisms ; Rhizosphere ; Phytophthora cinnamomi ; Phytophthora palmivora ; Root rot ; Avocado ; Schinus molle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Application to soil of 1 g (recommended rate) or 10 g l-1 of phosphonate did not affect the numbers of bacteria and fungi nor the proportions of actinomycetes and fungi antagonistic to Phytophthora cinnamomi. Foliar phosphonate applications to avocado seedlings (Persea americana) did not affect microbial numbers or the proportions of microbes in the rhizosphere capable of antagonizing P. cinnamomi. Mycelium of P. cinnamomi and zoospores of P. palmivora did not appear to respond to diffusates from excised roots of phosphonate-treated avocado and pepper-corn tree (Schinus molle) seedlings, respectively. However, less extensive lesions were observed on the roots of fungicide-treated avocado and pepper-corn tree seedlings exposed to P. cinnamomi and P. palmivora, respectively. The reduction in P. cinnamomi infection on pepper-corn tree seedlings appears to be brought about by additive rather than interactive effects of the resident soil microflora and foliar-applied phosphonate.
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    Bacteria-grazing amoebae in situ in the rhizosphere (1991)
    Springer
    Biology and fertility of soils 11 (1991), S. 83-87 
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    ISSN: 1432-0789
    Keywords: Amoebae ; Protozoa ; Rhizosphere ; Nutrient cycling ; Biocontrol ; Microaggregates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An ultrastructural investigation of amoebae in situ in the rhizosphere showed that the protozoa are closely associated with soil aggregates and produce long pseudopodia that penetrate micropores. This could partly explain why bacteria are generally confined to the interiors of microaggregates. The presence of cytologically intact and partly digested bacteria in the food vacuoles indicates that rhizosphere bacteria are both ingested and digested by the amoebae. This digestion could lead to the recycling of P and N immobilized in rhizosphere microorganisms.
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    Occurrence of vesicular-arbuscular mycorrhizae with Amaranthaceae in soils of the Indian semi-arid region (1991)
    Springer
    Biology and fertility of soils 11 (1991), S. 140-144 
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    ISSN: 1432-0789
    Keywords: Endogonaceous ; Vesicular-arbuscular mycorrhiza ; Endomycorrhiza ; Symbiosis ; Amaranthaceae ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Some members of the family Amaranthaceae, which has mostly been reported as non-mycorrhizal, were examined for a symbiotic association with mycorrhizae in the semiarid and arid zones. Ten species belonging to five genera, Achyranthes, Aerva, Alternanthera, Amaranthus, and Celosia were examined, using 1.0-cm long root standards. Intercellular hyphae, vesicles and arbuscules were observed in the root cortex. The number of different types of spores in the rhizosphere soil of different plants ranged from one to three. The spores isolated represented nine species belonging to four genera, Glomus, Gigaspora, Sclerocystis, and Scutellospora. No correlation could be established between spore counts and either soil pH or soil moisture.
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    Diversity of diazotroph populations in the rhizosphere of maize (Zea mays L.) growing on different French soils (1991)
    Springer
    Biology and fertility of soils 11 (1991), S. 210-215 
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    ISSN: 1432-0789
    Keywords: Rhizosphere ; Maize ; Bacillus circulans ; Enterobacteriaceae ; Nitrogen fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We studied the dominant diazotrophs associated with maize roots and rhizosphere soil originating from three different locations in France. An aseptically grown maize plantlet, the “spermosphere model”, was used to isolate N2-fixing (acetylene-reducing) bacteria. Bacillus circulans was the dominant N2-fixing bacterium in the rhizosphere of maize-growing soils from Ramonville and Trogny, but was not found in maize-growing sandy soil from Pissos. In the latter soil, Enterobacter cloacae, Klebsiella terrigena, and Pseudomonas sp. were the most abundant diazotrophs. Azospirillum sp., which has been frequently reported as an important diazotroph accociated with the maize rhizosphere, was not isolated from any of these soils. The strains were compared for their acetylene-reducing activity in the spermosphere model. The Bacillus circulans strains, which were more frequently isolated, also exhibited significantly greater acetylene-reducing activity (3100 nmol ethylene day-1 plant-1) than the Enterobacteriaceae strains (180 nmol ethylene day-1 plant-1). This work indicates for the first time that Bacillus circulans is an important maizerhizosphere-associated bacterium and a potential plant growth-promoting rhizobacterium.
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    Nitrogen fixation by Azospirillium brasilense in soil and the rhizosphere under controlled environmental conditions (1991)
    Springer
    Biology and fertility of soils 12 (1991), S. 100-106 
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    ISSN: 1432-0789
    Keywords: Azospirillum ; 15N-isotope dilution ; Nitrogen fixation ; Acetylene reduction activity ; ARA ; Rhizosphere ; Mineral nitrogen ; Oxygen tension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Acetylene reduction activity by Azospirillum brasilense, either free-living in soils or associated with wheat roots, was determined in a sterilised root environment at controlled levels of O2 tension and with different concentrations of mineral N. In an unplanted, inoculated soil nitrogenase activity remained low, at approximately 40 nmol C2H4 h-1 per 2kg fresh soil, increasing to 300 nmol C2H4 h-1 when malic acid was added as a C source via a dialyse tubing system. The N2 fixation by A. brasilense in the rhizosphere of an actively growing plant was much less sensitive to the repressing influence of free O2 than the free-living bacteria were. An optimum nitrogenase activity was observed at 10 kPa O2, with a relatively high level of activity remaining even at an O2 concentration of 20 kPa. Both NO inf3 sup- and NH inf4 sup+ repressed nitrogenase activity, which was less pronounced in the presence than in the absence of plants. The highest survival rates of inoculated A. brasilense and the highest rates of acetylene reduction were found in plants treated with azospirilli immediately after seedling emergence. Plants inoculated at a later stage of growth showed a lower bacterial density in the rhizosphere and, as a consequence, a lower N2-fixing potential. Subsequent inoculations with A. brasilense during plant development did not increase root colonisation and did not stimulate the associated acetylene reduction. By using the 15N dilution method, the affect of inoculation with A. brasilense in terms of plant N was calculated as 0.067 mg N2 fixed per plant, i.e., 3.3% of the N in the root and 1.6% in the plant shoot were of atmospheric origin. This 15N dilution was comparable to that seen in plants inoculated with non-N2-fixing Psudomonas fluorescens.
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    Use of aliette, a basipetally translocated antimicrobial compound, to enhance rhizophere colonization and nodulation by root-nodule bacteria (1991)
    Springer
    Biology and fertility of soils 12 (1991), S. 141-146 
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    ISSN: 1432-0789
    Keywords: Aliette ; Colonization ; Fungicide ; Rhizobia ; Rhizosphere ; Bradyrhizobium japonicum ; Alfalfa ; Medicago sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A method was developed to improve the colonizing ability of inoculated strains of root-nodule bacteria using aliette (aluminum tris-O-ethyl phosphonate), a basipetally translocated fungicide. Aliette applied to seeds of alfalfa inoculated with an aliette-resistant strain of Rhizobium meliloti increased the numbers of R. meliloti in the rhizosphere after 3 but not 37 days, increased the number of nodules, and with some seed treatments, increased the growth of alfalfa. The enhanced colonization by R. meliloti as a result of seed treatment with aliette lasted for at least 31 days for alfalfa, although plant weights did not increase, Colonization by R. meliloti was further enhanced if seeds and foliage were treated with the fungicide. Coating seeds or sparaying the foliage with aliette also increased the number and weight of nodules and nitrogenase activity in soybeans inoculated with an aliette-resistant strain of Bradyrhizobium japonicum. The stimulation of B. japonicum in the rhizosphere and of nodulation was evident with successive plantings of soybeans if the seeds for each planting were treated with the chemical, but aliette did not increase the yield of inoculated soybeans in the subsequent plantings. With only the seeds of the first planting of inoculated soybeans treated with aliette, the numbers of B. japonicum in the rhizosphere of subsequent plantings were only occasionally greater and the numbers of nodules on the later plantings were not increased. We suggest that root colonization, nodulation, and N2 fixation by Rhizobium and Bradyrhizobium may be enhanced by the use of basipetally translocated antimicrobial compounds together with root-nodule bacteria that are resistant to those compounds.
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    Microbial growth and nitrogen immobilization in the root zone of barley (Hordeum vulgare L.), Italian ryegrass (Lolium multiflorum Lam.), and white clover (Trifolium repens L.) (1991)
    Springer
    Biology and fertility of soils 12 (1991), S. 154-160 
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    ISSN: 1432-0789
    Keywords: Rhizosphere ; Bacterial counts ; Microbial biomass ; N immobilization ; Soil organic N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of roots on microbial growth and N immobilization was investigated in a pot experiment with barley, Italian ryegrass, and white clover. We used a silty subsoil with a low soil organic matter content (0.16%C and 0.012%N), which allowed us to measure N immobilization as an increase in total soil organic N (planted versus unplanted). At sampling, the soil was easily removed from intact roots by gentle washing, with a negligible loss of root material. Plant growth and extra mineral N (in planted soil only) gave increased total counts (fluorescence microscopy) and viable counts (plate dilution) of bacteria, a higher proportion of larger cells, and increased viable counts as a percentage of total counts. Under monocots, 12–17% of the added fertilizer N was recovered as soil organic N. Although this N immobilization was attributed to microbial assimilation, less than 1/4 was actually recovered as microbial biomass N, as measured with the chloroform fumigation/N-extraction method or calculated from total bacterial counts. The white clover accumulated substantial amounts of N due to N2 fixation. However, microbial N immobilization represented only 3% of the total N accumulation, showing that the microorganisms obtained a smaller share of biologically fixed N2 than of the N applied as fertilizer. Extra additions of mineral N (monocots) enhanced microbial N assimilation, partly due to increased plant growth. The results also strongly indicated, however, that the microbial growth under monocots was N-limited in the latter part of the experiment and that fertilizer N had a direct effect on microbial growth. In the early phase of plant growth, N immobilization ranged from 33 to 58 mg N g-1 root C. This level of immobilization required a release of organic C into the soil representing a minimum of 60–100% of that found in intact roots.
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    Effects of substrate sterilization, fungicide treatment, and mycorrhization helper bacteria on ectomycorrhizal formation of pedunculate oak (Quercus robur) inoculated with Laccaria laccata in two peat bare-root nurseries (1992)
    Springer
    Biology and fertility of soils 13 (1992), S. 55-57 
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    ISSN: 1432-0789
    Keywords: Bacteria ; Ectomycorrhiza ; Laccaria laccata ; Quercus robur ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Pedunculate oak seedlings (Quercus robur) inoculated with the ectomycorrhizal fungus Laccaria lacata were grown for 1 year on fertilized sphagnum peat in two nurseries. Three factors affecting microbial populations in the substrate were studied, fungicide treatment of the seeds, peat disinfection before sowing (methyl bromide or steam pasteurization), and inoculation with mycorrhization helper bacteria. Treatment of acorns with Iprodione had no depressive effect on mycorrhiza formation. Both disinfection techniques were equivalent, stimulating or depressing mycorrhiza formation depending on the initial microflora in the peat. The introduction of two previously selected mycorrhization helper bacteria (one Pseudomonas fluorescens and one unidentified fluorescent pseudomonad), isolated from L. laccata sporocarps associated with Douglas fir—L. laccata ectomycorrhizas in other nurseries, significantly increased the mycorrhizal rate from 30 to 53% of the short roots. The implications of these results for the controlled mycorrhization of planting stocks and the specificity of mycorrhization helper bacteria are discussed.
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    Survival of, and root colonization by, alginate-encapsulated Pseudomonas fluorescens cells following introduction into soil (1992)
    Springer
    Biology and fertility of soils 14 (1992), S. 14-22 
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    ISSN: 1432-0789
    Keywords: Pseudomonas fluorescens ; Alginate beads ; Soil ; Rhizosphere ; Rhizoplane ; Survival ; Root colonization ; Inoculation technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The survival of Pseudomonas fluorescens cells encapsulated in alginate beads and colonization of wheat roots was studied in soil microcosms inoculated with the cells in alginate beads of varying composition. Cells encapsulated in beads and introduced into a non-sterile loamy sand survived better than cells added directly to the same soil. A recovery/growth step for the bead-encapsulated cells was added before they were introduced into the soil, in an attempt to obtain optimal population levels in the soil. Further, bacterial populations that grew to the highest density in the beads subsequently showed the highest survival levels in soil. The addition of 3% skim milk, or 3% skim milk and 3% bentonite clay to all bead types consistently resulted in the highest survival of the encapsulated cells in soil. Root colonization by P. fluorescens was generally not impaired by the encapsulation in alginate. One week after inoculation into the soil, encapsulated cells in the various bead types were able to colonize the wheat rhizoplane at high population levels, similar to or exceeding those found when free cells were inoculated. In a second root colonization experiment the wheat rhizoplane was also efficiently colonized 7 weeks after the inoculant cells had been introduced into the soil in different bead types. In both assays, the cells encapsulated in beads amended with skim milk plus bentonite clay showed the highest root colonization rates. It is clear, therefore, that alginate-mediated establishment of inoculants can improve inoculant effectiveness.
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    Techniques for observing phosphorus mobilization in the rhizosphere (1992)
    Springer
    Biology and fertility of soils 14 (1992), S. 121-125 
    Details
    ISSN: 1432-0789
    Keywords: Rhizosphere ; Calcium phosphate solubilization ; Nitrogen source ; Acidification ; Phosphatase activity ; Phenolphthalein phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The techniques described here were developed to visualize the dissolution of sparingly soluble calcium phosphate and the presence of root-borne phosphatase in the rhizosphere. Newly formed calcium phosphate precipitate was suspended in agar containing other essential nutrients. The agar was poured into Petri dishes and acrylglass boxes and was used as a growth medium for seedlings of wheat, rape, buckwheat, and rice. With NH 4 + applied as the N source, the precipitate dissolved in the root vicinity and this was attributed to acidification. No dissolution occurred with NO 3 − as the N source. The release of a neutral phosphatase from roots was verified by embedding the roots of young seedlings in agar at pH 7 containing phenolphthalein phosphate. After pH was raised to the alkaline range by adding sodium hydroxide, the agar around the roots turned purple, especially around the roots of P-deprived plants. The most intensive phosphatase activity was found in apical root regions.
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    URL: http://dx.doi.org/10.1007/BF00336261
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    Influence of a plant growth-promoting pseudomonad and vesicular-arbuscular mycorrhizal fungus on alfalfa and birdsfoot trefoil growth and nodulation (1992)
    Springer
    Biology and fertility of soils 14 (1992), S. 175-180 
    Details
    ISSN: 1432-0789
    Keywords: Rhizobia ; Rhizosphere ; Acid soils ; Pastures ; Hill-lands ; Vesicular arbuscular mycorrhizal ; Pseudomonas putida ; Plant growth-promoting rhizobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In a growth chamber study we examined the influence of a plant growth-promoting rhizobacterium, Pseudomonas putida R-20, and an acid-tolerant vesicular-arbuscular mycorrhizal (VAM) fungus, Glomus intraradices 25, on Medicago sativa L. and Lotus corniculatus L. growth and nodule development. Seedlings were planted in an acidic (pH 5.5), P-deficient soil containing re-established native microflora (minus VAM) and appropriate rhizobia, and inoculated with the rhizobacterium, the VAM fungus, or both. The plants were assayed at three intervals for up to 10–11 weeks. The growth-promoting rhizobacteria alone increased alfalfa shoot mass by 23% compared to all other treatments, but only at 8 weeks of growth, apparently by promoting nodulation and N2 fixation (acetylene reduction activity). The presence of VAM, either alone or in combination with the rhizobacteria, generally decreased root length but only at 8 weeks also. As a group, the inoculation treatments increased all nodular measurements by 10 weeks of growth. Few treatment effects were found at 7 and 9 weeks for birdsfoot trefoil; neither plant nor nodular measurements differed among treatments. By 11 weeks, shoot mass was increased by the rhizobacteria alone by 36% compared to the control. As a group, the inoculation treatments all showed increased nodular responses by this time. The rhizobacteria stimulated mycorrhizal development on both plant species, but only at the initial samplings. No synergistic effects between the plant growth-promoting rhizobacterium and VAM inoculation were found. Although these results lend credence to the concept of managing microorganisms in the rhizosphere to improve plant growth, they emphasize the necessity for a more thorough understanding of microbial interactions as plants mature.
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    Fluctuations in bacterial populations on the root surface of wheat (Triticum aestivum L.) grown under different soil conditions (1992)
    Springer
    Biology and fertility of soils 14 (1992), S. 246-252 
    Details
    ISSN: 1432-0789
    Keywords: Volcanic ash soil ; Fluorescent pseudomonads ; Rhizosphere ; Wheat ; Bacterial groups ; Phosphate fertilizer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Populations of several bacterial groups on the root surface of wheat and in root-free soil were investigated in volcanic ash soil and non-volcanic ash soil throughout a series of predetermined intervals. Over time, the populations changed similarly both on the root surface and in root-free soil. The numbers of total bacteria, fluorescent Pseudomonas spp., phosphate-solubilizing bacteria, and NH inf+ sup4 -oxidizing bacteria, were consistently lower in the plots with volcanic ash soil than with nonvolcanic ash soil, but the numbers of cellulose-decomposing bacteria were opposite to those of the other groups. Superphosphate application improved the growth of wheat in the volvanic ash soil. It did not, however, bring about any significant changes in the bacterial populations among the volcanic ash soils supplemented with three different levels of superphosphate, though there were some variations with plant age.
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    URL: http://dx.doi.org/10.1007/BF00395459
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    Effects of pine roots on microorganisms, fauna, and nitrogen availability in two soil horizons of a coniferous forest spodosol (1993)
    Springer
    Biology and fertility of soils 15 (1993), S. 113-119 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Microarthropods ; Nematodes ; Rhizosphere ; Disturbance ; Microcosm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We investigated the effects of pitch pine seedling roots on extractable N, microbial growth rate, biomass C and N, and nematodes and microarthropods in microcosms with either organic (41% C, 1.14% N) or mineral (0.05% C, 0.01% N) horizon soils of a spondosol. Root quantity was manipulated by varying plant density (0, 1, 2, or 4 seedlings) and rhizosphere soil was separated from non-rhizosphere soil by a 1.2 μm mesh fabric. In the rhizosphere of organic soil horizons, moisture, microbial growth rate, biomass C and N, and extractable N declined as root density was increased, but there was little effect on nematodes or microarthropods. High levels of extractable N remained after 5 months, suggesting that N mineralization was stimulated during the incubation. In the rhizosphere of mineral soil horizons, microbial growth rate, and nematode and microarthropod abundances increased at higher root density, and in the absence of roots faunal abundance approached zero. Faunal activity was concentrated in the rhizosphere compared to non-rhizosphere soil. In organic soil horizons, roots may limit microbial activity by reducing soil moisture and/or N availability. However, in mineral soil horizons, where nutrient levels are very low, root inputs can stimulate microbial growth and faunal abundance by providing important substrates for microbial growth. Our results demonstrate a rhizosphere effect for soil fauna in the mineral soil, and thus extends the rhizosphere concept to components of the soil community other than microbes for forest ecosystems. Although our results need to be verified by field manipulations, we suggest that the effects of pine roots on nutrient cycling processes in coniferous forests can vary with soil nutrient content and, therefore, position in the soil profile.
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    Effects on yield and nutrition of mycorrhizal and nodulated Pueraria phaseoloides exerted by P-solubilizing rhizobacteria (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 23-29 
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    ISSN: 1432-0789
    Keywords: Mycorrhiza ; Glomus sp. ; P-solubilizing bacteria ; Phytate-mineralizing rhizobacteria ; Pueraria phaseoloides ; Rhizosphere ; Unavailable P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the effect of bacteria involved in rock phosphate (four isolates), iron phosphate (two isolates), and aluminium phosphate (two isolates) solubilization, and two phytate-mineralizing bacteria in terms of their interaction with two Glomus spp. on Pueraria phaseoloides growth and nutrition. The plant —Rhizobium sp. — mucorrhiza symbiosis system may increase in yield and nutrition in association with specific rhizosphere bacteria that solubilize calcium, iron, and aluminium phosphates. No benefit from phytate-mineralizing bacteria was found under these experimental conditions. P. phaseloides growth responses were influenced in different ways by specific combinations of the selected bacteria and arbuscular mycorrhizal fungi. Considerable stimulation of nutrient uptake was observed with fungus-bacteria combinations of Azospirillum sp. 1, Bacillus sp. 1 or Enterobacter (spp. 1 or 2) associated with G. mosseae. The fact that Bacillus sp. 1, a calcium-phosphate solubilizing isolate, positively interacted with G. mosseae and negatively with G. fasciculatum is an indication of specific functional compatibility between the biotic components integrated in the system. From our results, the interactions between bacterial groups able to solubilize specific phosphate and mycorrhizal fungi cannot be interpreted as occurring only via P solubilization mechanisms since no generalized effect was obtained. Iron-phosphate solubilizing microorganisms were more active alone than in dual associations with Glomus sp., but the aluminium-phosphate dissolving isolates positively interacted in mycorrhizal plants. Further work is needed in this area in order to elucidate the mechanisms that affect rhizosphere microorganism interactions. G. mosseae was more effective but less infective than G. fasciculatum in most of the combined treatments.
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    Estimating microbial biomass N in soils with and without living roots: Limitations of a pre-extraction step (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 314-318 
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    ISSN: 1432-0789
    Keywords: Key words Microbial biomass N ; Fumigation-extraction ; Pre-extraction ; Rhizosphere ; Roots ; Net-closed soil containers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Special net-closed soil containers were used in a pot experiment with low and high plant densities to give soil samples with and without roots. Soils from the containers were analysed either by the fumigation-extraction method or by a modified procedure starting with a pre-extraction and sieving step to remove plant roots from the samples. In the extracts NO-N, NH-N, organic N, and total N were measured. Microbial biomass N was calculated from the differences in total N in fumigated and unfumigated soils. Different plant densities had almost no influence on the values of the N compounds using either method. In soils with roots, significantly more organic N (and total N) was found by the fumigation-extraction method compared to soils without roots while no differences were obtained using pre-extractions and sieving. Though the organic N content in pre-extracts from soils with roots was significantly higher than from soils without roots, the NO-N and NH-N content was lower. Significant differences in biomass N in soils with and without roots were found only with the fumigation-extraction method. Biomass N levels calculated using the results after pre-extraction and sieving were about 50% lower than levels detected using fumigation-extraction alone. With the use of special net-closed soil containers, not only were soil samples produced with and without roots, but it was also possible to induce a rhizophere in the soils. A comparison of the two methods using these soils clearly demonstrated that the method used has profound influence on the final biomass N results. While higher ”biomass“ levels were found by fumigation-extraction in soils with roots, because root N becomes extractable after fumigation, the use of a pre-extraction and a sieving step may underestimate the total biomass N content due to the pre-extraction of microbial N (especially from rhizosphere microorganisms) from the sample. Nevertheless, pre-extraction and sieving followed by fumigation-extraction does seem to be the preferable method for biomass N measurement in comparative studies, because in most cases only minor errors will occur.
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    Endomycorrhizae in a newly cultivated acidic meadow: Effects of three years of barley cropping, tillage, lime, and phosphorus on root colonization and soil infectivity (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 160-165 
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    ISSN: 1432-0789
    Keywords: Hordeum vulgare ; Agricultural ecosystem ; Acidic soil ; Soil infectivity ; Endomycorrhizae ; Reduced tillage ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The dynamics of mycorrhizae under disturbance created by crop production is not well understood. A 3-year experiment was undertaken on a nutrient-poor and acidic land that had last been cultivated in the early 1970s. We observed the effects of cropping spring barley (Hordeum vulgare L.) under four P-fertilizer levels and four levels of lime, in a minimum (rototillage), a reduced (chisel), or a conventional tillage system, on the mycorrhizal receptiveness of the host (maximum level of mycorrhizal colonization, as measured at harvest) and soil infectivity most probable number method. The host receptiveness decreased with time, while crop yields and soil infectivity increased simultaneously with time. Liming increased mycorrhizal colonization of barley roots and soil infectivity. P additions decreased root colonization but did not significantly affect the most probable number valuse. Slightly higher soil infectivity estimates were found under reduced tillage.
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    A ferrotantalite-ferrotapiolite intergrowth from Spittal a.d. Drau, Carinthia, Austria (1989)
    Springer
    Mineralogy and petrology 41 (1989), S. 53-63 
    Details
    ISSN: 1438-1168
    Keywords: Tantalum ; niobium ; tantalite ; tapiolite ; mineralogy ; geochemistry ; pegmatite ; Ostalpen ; Austria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung In einem Pegmatit von Spittal a.d. Drau, Kärnten, treten enge Verwachsungen von Ferrotantalit und Ferrotapiolit auf. Diese werden von Muskovit, Albit, Rauchquarz, Zinnstein sowie-in mikroskopischem Masstab-von Uranmikrolith und Zirkon begleitet. Die Textur der Verwachsungen lässt Rekristallisation erheblichen Ausmasses erkennen, die die primären Merkmale weitgehend auslöscht. Weder eine gemeinsame Auskristallisation der beiden Mineralphasen noch eine Bildung durch Entmischung kann mit Sicherheit erkannt werden. Trotz einander kreuzender Verbindungslinien, die einen Hinweis auf Ungleichgewicht darstellen, zeigen die Zusammensetzungen des Ferrotantalits und des Ferrotapiolits lediglich geringe Schwankungsbreiten: Mn/(Mn + Fe) 0,08–0,11, Ta/(Ta + Nb) 0,53–0,57 für den Ferrotantalit beziehungsweise 0,01–0,04 und 0,84–0,89 für den Ferrotapiolit. Dies gilt insbesondere für den Vergleich mit Zusammensetzungen solcher Mineralphasen mit jenen von Fundarten, die primäre Verwachsungstrukturen aufweisen. Bis zu einem gewissen Ausmass ist diese homogene Zusammensetzung möglicherweise auf die Rekristallisation zurück zuführen. Diese Rekristallisation könnte auch den hohen strukturellen Ordnungsgrad der beiden Mineralphasen erklären. An anderen Fundorten zeigen diese Minerale strukturell merklich geringeren Ordnungsgrad. Intensive metamorphe überprägung, wie sie für die Pegmatite in den südlichen Ostalpen und insbesondere für jenen von Spittal typisch sind, kann wahrscheinlich als Ursache der Rekristallisationsphänomene der Ta-Nb-Sn Mineralparagenese angenommen werden.
    Notes: Summary Intimate intergrowths of ferrotantalite and ferrotapiolite occur in a pegmatite in Spittal a.d. Drau, Carinthia. They are associated with muscovite, albite, smoky quartz, cassiterite, and microscopic uranmicrolite, zircon and uraninite. An assemblage of secondary uranium minerals is also present, generated by extensive alteration and leaching of the uranmicrolite and zircon. Textures of the ferrotantalite-ferrotapiolite intergrowths suggest considerable recrystallization that obliterated most of their primary features; neither coprecipitation nor exsolution can be recognized with certainty. Despite intersecting tielines indicating disequilibrium, the ferrotantalite and ferrotapiolite compositions show very restricted ranges (Mn/(Mn + Fe) 0.08–0.11, Ta/(Ta + Nb) 0.53–0.57 for ferrotantalite, and 0.01–0.04, 0.84–0.89 for ferrotapiolite, respectively), particularly in comparison with compositions from other localities featuring primary textures. A degree of compositional equilibration could have been attained during recrystallization. This process may also explain the high level of structural order characterizing both minerals; they are considerably disordered in other localities. Extensive deformation typical of pegmatites in the southern Ostalpen in general, and specifically of the Spittal pegmatite, is probably responsible for the recrystallization phenomena in the Ta, Nb, Sn-bearing mineral assemblage.
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    Statistical estimation of mineral age by K-Ar method (1989)
    Springer
    Mathematical geology 21 (1989), S. 905-919 
    Details
    ISSN: 1573-8868
    Keywords: convolution of distributions ; uniform distribution ; normal distribution ; Gul'shad Massif ; potassium-argon dating ; geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Statistical estimation of age of40Ar/40K ratios may be considered a result of convolution of uniform and normal distributions with different weights for different minerals. Data from Gul'shad Massif (Nearbalkhash, Kazakhstan, USSR) indicate that40Ar/40K ratios reflecting the intensity of geochemical processes can be resolved using convolutions. Loss of40Ar in bioties is shown whereas hornblende retained the original content of40Ar throughout the geological history of the massif. Results demonstrate that different estimation methods must be used for different minerals and different rocks when radiometric ages are employed for dating.
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    An empirical discriminant method applied to sedimentary-rock classification from major-element geochemistry (1971)
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    Mathematical geology 3 (1971), S. 51-60 
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    ISSN: 1573-8868
    Keywords: entropy ; principal components analysis ; geochemistry ; mineralogy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Classification of sandstones, greywackes, pelites, limestones, dolomites, and acid-igneous and basicigneous rocks, using a literature sample of 183 post-1920 analyses for the 11 major oxides has achieved an 80-percent success rate. The method is based on nonparametric estimation of a probability density function for each category to be classified, using the Bayes decision rule. The method is suitable for use with small training sets and gives much improved results over a linear discriminant function. Classification following data compression using principal components also has given satisfactory recognition rates.
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    Geostatistical investigations of gabbro occurrences near Savantvadi, Ratnagiri district, India (1972)
    Springer
    Mathematical geology 4 (1972), S. 147-153 
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    ISSN: 1573-8868
    Keywords: classification ; statistical inference ; statistics ; geochemistry ; petrochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract This paper embodies petrographical and statistical investigations of three gabbro occurrences. The Mangaon and Kunkeri gabbros are similar in petrography and petrochemistry, whereas they are completely different from the Vajrat gabbro. Application of recently developed statistical tests help in classifying these gabbros by using three oxides, CaO, FeO, and K2O.This study shows that the evolution of the Mangaon and Kunkeri gabbros probably proceeded along different lines as compared to the Vajrat gabbro.
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    Analysis of multivariate point distributions and chemical grouping of rocks (1975)
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    Mathematical geology 7 (1975), S. 191-214 
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    ISSN: 1573-8868
    Keywords: classification ; cluster analysis ; mapping ; multivariate analysis ; pattern recognition ; point-density analysis ; geochemistry ; ore-bearing districts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Large sets of rock compositions can be grouped by the analysis of corresponding point distributions in multidimensional space, where the separate dimensions represent the chemical variables. The point density around each composition is estimated in a small, multivariate, rectangular interval. Establishment of the identity of specimens contained in the interval, and systematic comparison of the point densities surrounding each of them, leads to the recognition of density maxima, which represent the statistical modes of the rock types present in the set. The remaining specimens by the same operations can be assigned to the groups formed. Experimental results are given for two sets, one comprising a wide variety of metasedimentary and metavolcanic rocks from the ore-bearing Skellefte district and adjacent parts of Västerbotten, Sweden, and the other representing a less variable population of basic rocks from Norrbotten, Sweden. Linear discriminant analysis and existing geological information indicate that the groups obtained are statistically and geologically valid.
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    Dynamical formulation of Broecker's model for marine cycles of biologically incorporated elements (1976)
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    Mathematical geology 8 (1976), S. 511-527 
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    ISSN: 1573-8868
    Keywords: analogcomputer simulation ; systems analysis ; geochemistry ; oceanography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Broecker presented a steady-state, two-box model which emphasizes the role of kinetic factors in determining the chemical composition of sea water. Unlike thermodynamic models, Broecker's model suggests that sizable temporal variation in the composition of sea water and rates of sedimentation may have taken place in the past 100 million years. To describe the evolution of the ocean's chemical system and interpret variations observed in the sedimentary record, we have formulated a dynamical model. Mass-balance consideration leads to a set of coupled nonlinear differential equations. The equations are linearized and solved for step function changes in the rate of river input and in the rate of vertical mixing. This simple model of the ocean's chemical system is shown to be stable against oscillations. Using data for the modern ocean, the response times for P, C, Si, Ca, and Ba are calculated to be of the order of 104 to 106 yr for changes in river and other inputs and of the order 101 to 102 yr for a change in the rate of vertical mixing. Analog-simulation techniques, discussed for the situation of the two-box model, provide a powerful tool for treating nonlinearities and systems with more than two components. In the final section, consequences of the dynamical formulation are compared with parameters appearing in Broecker's steady-state formulation.
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    Mineral variation in anorthositic, troctolitic, and adamellitic rocks of the Barth Island layered structure in the Nain anorthosite complex, Labrador (1976)
    Springer
    Mathematical geology 8 (1976), S. 561-574 
    Details
    ISSN: 1573-8868
    Keywords: regression analysis ; trend analysis ; geochemistry ; petrology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The Barth Island layered structure is an oval, 6 by 9 km body, consisting of rhythmically layered adamellitic rock in the center which grades outward through jotunite into troctolite. Farther outward the sequence repeats itself in reversed order, strongly reduced in magnitude and finer grained; the adamellitic zone is followed by jotunite which grades into coarse-grained leuconorite and into anorthosite of the Nain complex. The Barth Island structure, having an inverted conical base topped by a hemispherical depression, seems to represent a distorted sequence of rock layers with troctolite at the bottom, grading upward into adamellitic rocks which grade into anorthosite at the top. Trend-surface analysis demonstrates the regional variation of plagioclase and orthopyroxene compositions in the troctolite—adamellite sequence of the central part of the structure. The fits for the second- and third-degree surfaces are good and significant at the 99 percent level. The regression line for compositional variation in coexisting plagioclase and orthopyroxene in all analyzed rocks has a correlation coefficient of r2 = 0.78. The difference between the trends in the troctolite—adamellite sequence and the anorthosite—adamellite sequence is insignificant. The regression curve for compositional variation in coexisting orthopyroxene and olivine has a correlation coefficient of r2 = 0.98. The curve shows good correlation with the experimentally established partitioning curve of Medaris, which indicates that equilibrium conditions prevailed during formation of the olivine—ortho-pyroxene pairs. The results suggest that the troctolite—adamellite sequence and the anorthosite—adamellite sequence are products of fractional crystallization, possibly from the same parental magma.
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    Application of some correlation coefficient techniques to time-series analysis (1974)
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    Mathematical geology 6 (1974), S. 363-372 
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    ISSN: 1573-8868
    Keywords: autocorrelation ; crosscorrelation ; time series ; geochemistry ; sedimentology ; stratigraphy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Application of the sliding correlation technique has permitted detailed stratigraphic correlation over entire basins. The main values of the technique are to (1) demonstrate correlation statistically, (2) extend the range of visual correlation, and (3) establish precise correlation where correlation is known to exist but is difficult to establish visually. The technique is especially valuable in aiding correlation of stratigraphic sequences such as varves and turbidites, which are characterized by monotonous repetition of two or more lithologic components. The moving correlation technique is a valuable aid in examining variations in degree of correlation between correlative sections, and in analysis of component associations within a single stratigraphic sequence.
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    Application of correspondence factor analysis to the study of major and trace elements in the Erta Ale Chain (Afar, Ethiopia) (1975)
    Springer
    Mathematical geology 7 (1975), S. 13-30 
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    ISSN: 1573-8868
    Keywords: correspondence analysis ; factor analysis ; geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The lavas in the active volcanic chain of the Erta Ale were emplaced 1 million years ago on the new crust of oceanic character created by the separation of the Arabic plate and the African plate. This differentiated series ranges from the basalts to the hyperalkaline rhyolites, passing through all the intermediate members. It is characterized by an iron enrichment in the intermediate series, and the role of silica is secondary in the differentiation which is controlled by the fractionation of olivine, pyroxene, and calcic plagioclases. By applying correspondence factor analysis to the rock samples analyzed for major and trace elements, factors were found expressing the importance of certain associations between the samples and their elements. The variables were projected onto factorial axes and graphs were plotted automatically showing their positions. Ellipses corresponding to the groups based on the rock types, volcanoes, and the indices of Kuno were drawn so that their situation in relation to the oxides and trace elements could be seen. From the plan of the axes, the degree of differentiation of the samples in the considered series is indicated, and the petrological terminology of the rocks may be verified. Two graphs, representing the series, are proposed using indices for the oxides and traces obtained from the results of correspondence analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02080631
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    On the need, design, and prospects for an electronic information system serving igneous petrology (1975)
    Springer
    Mathematical geology 7 (1975), S. 363-371 
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    ISSN: 1573-8868
    Keywords: data processing ; geochemistry ; petrology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract An information system is needed to restore access to published information, now so voluminous that suitable levels of familiarity with it cannot be maintained by conventional nonelectronic scholarly devices. The services of the system should be available to petrologists via mail or remote terminal, and should provide, as requested, either retrieval or reduction of data contained in its base. The base should contain chemical, geological, mineralogical, and petrographic information about specimens for which full descriptions have been published. Provisional plans for construction of such a base are briefly reviewed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02080495
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    Principal components analysis using the hypothetical closed array (1976)
    Springer
    Mathematical geology 8 (1976), S. 25-36 
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    ISSN: 1573-8868
    Keywords: principal components analysis ; closure correlations ; geochemistry ; petrology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The application of R-mode principal components analysis to a set of closed chemical data is described using previously published chemical analyses of rocks from Gough Island. Different measures of similarity have been used and the results compared by calculating the correlation coefficients between each of the elements of the extracted eigenvectors and each of the original variables. These correlations provide a convenient measure of the contribution of each variable to each of the principal components. The choice of similarity measure (variance-covariance or correlation coefficient)should reflect the nature of the data and the view of the investigator as to which is the proper weighting of the variables—according to their sample variance or equally. If the data are appropriate for principal components analysis, then the Chayes and Kruskal concept of the hypothetical open and closed arrays and the expected closure correlations would seem to be useful in defining the structure to be expected in the absence of significant departures from randomness. If the data are not multivariate normally distributed, then it is possible that the principal components will not be independent. This may result in significant nonzero covariances between various pairs of principal components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01039682
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    An abundance model resource appraisal for some Canadian commodities (1978)
    Springer
    Mathematical geology 10 (1978), S. 481-494 
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    ISSN: 1573-8868
    Keywords: geochemistry ; crustal abundance ; resource analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract An abundance model resource appraisal has been undertaken for 10 mineral commodities in Canada: nickel, copper, zinc, lead, molybdenum, uranium, silver, gold, chromium, and tin. The purpose of the appraisal was to investigate the applicability of the model to the Canadian situation. Resource appraisals for the first 6 of the commodities studied have been published following deposit modeling studies. For many other commodities studied have been published following deposit modeling appraisals. The demonstration of the relevance of the abundance model to Canada would allow its application in such cases. The data presented in this paper indicate that the approximate relation, resource (short tons)=abundance (%)×1010. holds true for all commodities studied except chromium and tin. As the resources versus abundances relationship observed on a global scale is observable in Canada, it is concluded that Canada is a sufficiently large fraction (∼7%) of the earth's continental crust to represent a valid sample of that crust. Canada appears to be relatively well endowed with resources of copper, molybdenum, lead, and zinc, and poorly endowed with chromium and tin. It is proposed that the intersection of national boundaries with the boundaries of the world's metallogenic provinces is of greater importance than the intensity of past search, a feature that has been suggested in other studies. If these areas overlap, a nation may be self sufficient in a commodity: if they do not, the nation must import, or find a nationally available substitute. The sources of information used in the appraisal are outlined together with an analysis of the problems encounterea and the time requirements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02461979
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    Application of a generalized power transformation to geochemical data (1979)
    Springer
    Mathematical geology 11 (1979), S. 45-62 
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    ISSN: 1573-8868
    Keywords: geochemistry ; frequency distributions ; data transformation ; algorithm ; FORTRAN
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract In the context of analysis of variance, Box and Cox (1964) developed a generalized technique for power transformation of frequency distributions to normality. It is here applied to geochemical data, based on the nonlinear optimization of skewness and kurtosis. The transform appears to be particularly well suited to the preprocessing of geochemical data prior to multivariate analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01043245
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    The use of correspondence analysis in geochemistry (1982)
    Springer
    Mathematical geology 14 (1982), S. 331-342 
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    ISSN: 1573-8868
    Keywords: Correspondence analysis ; extendedQ-mode factor analysis ; geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract When factor analysis is used in geochemistry, it may be useful for factors to be transformed by rotations in order to be identified either to the end members of a mixing model (Miesch, 1976a),or to known chemical equilibriums. It requires that the formula for recomputing data from the factors may be written in a factored manner, which is generally not the case in correspondence analysis. The present paper shows that this becomes possible with data having constant row sums. As an example, the method is tested on the lavas of Paricutin Volcano, already examined by using an extended Q-mode factor analysis (Miesch, 1979).Recomputation of the data after projection gives simular results for both methods. Otherwise, the fact that correspondence analysis provides centered factors makes it well suited to the study of chemical reactions leading to constant mass transformations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01032594
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    Application of time series analysis to the tectonic analysis of disturbed rock sequences recorded from drill hole logs with examples from the paleozoic of Graz (Austria) (1983)
    Springer
    Mathematical geology 15 (1983), S. 673-685 
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    ISSN: 1573-8868
    Keywords: autocorrelation ; cross correlation ; geochemistry ; spectral analysis ; tectonic structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Time series analysis (autocorrelation, cross correlation, spectral analysis)is used to reconstruct tectonic structures from geochemical drill hole log data. After segmentation of a log one obtains typical patterns of significant correlations by cross correlation analysis. These patterns can be included in a “log-segment-correlation matrix” (LSCM)and are interpreted as repetitions caused by fractures or as folds extending over one or more segments. Smaller tectonic structures can be detected by spectral analysis. Examples are given from Pb-Zn exploration drill holes in the Paleozoic of Graz (Austria).
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    URL: http://dx.doi.org/10.1007/BF01033231
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    The statistical analysis of geochemical compositions (1984)
    Springer
    Mathematical geology 16 (1984), S. 531-564 
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    ISSN: 1573-8868
    Keywords: Closure ; closed number system ; logistic ; logratio ; geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The analysis and interpretation of compositional data, such as major oxide compositions of rocks, has been traditionally plagued by the so-called constant-sum or closure problem. Particular difficulties have been the lack of a satisfactory, interpretable covariance structure and of rich, tractable, parametric classes of distributions on the simplex sample space. Consideration of logistic and logratio transformations between the simplex and Euclidan space has allowed the introduction of new concepts of covariance structure and of classes of logistic-normal distributions which have now opened up a substantial and meaningful array of statistical methodology for compositional data. From the motivation of a wide variety of practical geological problems we examine the range of possibilities with this new approach to the constant-sum problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01029316
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    Assessing Uncertainty Associated with the Delineation of Geochemical Anomalies (1999)
    Springer
    Natural resources research 8 (1999), S. 59-67 
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    ISSN: 1573-8981
    Keywords: Indicator kriging ; gold ; exploration ; geochemistry ; data analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A pedogeochemical exploratory survey of gold deposits was carried out in the region of São Sepé (southernmost Brazil). The region comprises a predominantly metamorphosed belt of volcanoclastics, sediments, serpentinites, basalts, gabbros, chert, tuffs, and banded iron formation of the Proterozoic age. The anomalies were identified first by stream sediment heavy mineral survey at the regional scale of exploration. Once spatial continuity was modeled, ordinary block kriging was performed to generate geochemical maps. Indicator block kriging also was used as an alternative in analyzing and interpreting geochemical data. A novel approach is proposed, which combines both ordinary and indicator kriging for delineating geochemical anomalies. Probability maps proved to be appropriate for selecting new sites for further exploration. Gold anomalies in soils trending NE were well defined by geostatistical analysis and subsequently confirmed by drilling.
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    URL: http://dx.doi.org/10.1023/A:1021633728396
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