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  • nitrogen  (227)
  • Springer  (227)
  • Periodicals Archive Online (PAO)
  • MDPI Publishing
  • 1990-1994  (227)
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  • Springer  (227)
  • Periodicals Archive Online (PAO)
  • MDPI Publishing
  • Wiley-Blackwell  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Glucoamylase production by Aspergillus niger on rice bran is improved by adding nitrogen sources (1994)
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 348-349 
    Details
    ISSN: 1573-0972
    Keywords: Aspergillus ; glucoamylase ; nitrogen ; rice bran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Corn steep liquor, peptone or NH inf4 sup+ salts increased the yield of glucoamylase from Aspergillus niger growing in a solid-state fermentation on rice bran up to 360 IU/g dry substrate over 96 h at 30°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00414878
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  • 2
    Electronic Resource
    Electronic Resource
    Phosphorus and nitrogen limitation of algal biomass across trophic gradients (1994)
    Springer
    Aquatic sciences 56 (1994), S. 16-28 
    Details
    ISSN: 1420-9055
    Keywords: Chlorophyll-a ; phosphorus ; nitrogen ; lake ecosystem ; nutrient limitation ; regression analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regression results based on data from 46 northern temperate lakes show that total phosphorus (TP) is the best predictor for phytoplankton (as chl-a) at lower trophic levels, TP 〈 200 mg · m−3. A regression including both TP and TN as regressors is the best predictor for lakes with TP 〉 200 mg · m−3. However, the good correlation is probably due to a high correlation between lake average chl-a (all years observed) and lake average TP and TN. Within single hypereutrophic lakes, TN alone is the best predictor. It was not possible to identify a medium trophic domain where TN and TP in combination was the best predictor for chl-a. The ratio TN:TP in the water decreases from about 40 to about 5 with increasing trophic level. Optimum TN:TP ratio for algal species with high abundance during late summer and autumn reflects this decreasing ratio, but within a lesser range, i.e., 20 to 5. In contrast, TN:TP ratios for species abundant during the early vernal period showed no, or an inverse, relation to the TN:TP ratio of the water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877432
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  • 3
    Electronic Resource
    Electronic Resource
    Crop nitrogen utilization and soil nitrate loss in a lettuce field (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 93-105 
    Details
    ISSN: 1573-0867
    Keywords: Erosion/Productivity Impact Calculator (EPIC) model ; leaching ; lettuce ; net N mineralization ; nitrate ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Low N use efficiency and high nitrate (NO 3 - ) pollution potentials are problems in intensive vegetable production systems. The purpose of this study was to quantify N utilization by lettuce (Lactuca sativa L. cv Salinas), and identify periods of NO 3 - loss in an on-farm study in the Salinas Valley in coastal California. During autumn and winter, surface moisture remained low, and NO 3 - concentrations increased, reflecting high net mineralizable N, as determined by anaerobic incubation, and nitrification potential, as determined by the chlorate inhibition method. At the onset of a large winter storm, tracer levels of15NO 3 - were injected in the top 5 mm of soil in 30 cm-deep cylinders. After two weeks, most of the15N was present as15NO 3 - at 10–30 cm depth. By difference, losses to denitrification accounted for ~ 25% of the surface-applied15N. Leaching below 30 cm did not occur, since no15N enrichment of NO 3 - -N was measured in anion-exchange resin membranes placed at the base of each cylinder. During the crop period, NO 3 - losses were most pronounced after irrigation events. Uptake of N by two crops of lettuce (above- and belowground material) was approximately equal to fertilizer inputs, yet simulation of N fates by the Erosion/Productivity Impact Calculator (EPIC) model indicated losses of 14.6 g-N m−2 by leaching and 2.5 g-N m−2 by denitrification during the 6-month crop period. The large NO 3 - losses can be attributed to accumulation of soil NO 3 - during winter that was leached or denitrified during the irrigated crop period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00748550
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  • 4
    Electronic Resource
    Electronic Resource
    Historical changes in sediments of Pyramid Lake, Nevada, USA: consequences of changes in the water balance of a terminal desert lake (1994)
    Springer
    Journal of paleolimnology 12 (1994), S. 87-101 
    Details
    ISSN: 1573-0417
    Keywords: Great Basin ; climatic variations ; productivity ; organic matter ; nitrogen ; phosphorus ; hardwater lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from the shallow and deep basins of Pyramid Lake, Nevada, revealed variations in composition with depth reflecting changes in lake level, river inflow, and lake productivity. Recent sediments from the period of historical record indicate: (1) CaCO3 and organic content of sediment in the shallow basin decrease at lower lake level, (2) CaCO3 content of deep basin sediments increases when lake level decreases rapidly, and (3) the inorganic P content of sediments increases with decreasing lake volume. Variations in sediment composition also indicate several periods for which productivity in Pyramid Lake may have been elevated over the past 1000 years. Our data provide strong evidence for increased productivity during the first half of the 20th Century, although the typical pattern for cultural eutrophication was not observed. The organic content of sediments also suggests periods of increased productivity in the lake prior to the discovery and development of the region by white settlers. Indeed, a broad peak in organic fractions during the 1800's originates as an increase starting around 1600. However, periods of changing organic content of sediments also correspond to periods when inflow to the lake was probably at extremes (e.g. drought or flood) indicating that fluctuations in river inflow may be an important factor affecting sediment composition in Pyramid Lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678089
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  • 5
    Electronic Resource
    Electronic Resource
    Coupling of dry matter and nitrogen accumulation in ryegrass (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 105-108 
    Details
    ISSN: 1573-0867
    Keywords: annual ryegrass ; dry matter ; logistic ; model ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The logistic model has proven very useful in relating dry matter production of warm season perennial forage grasses to applied nitrogen. A recent extension of the model coupled dry matter and plant N accumulation through a common response coefficient c. The objective of this analysis was to apply the extended logistic model to cool season Gulf annual ryegrass (Lolium multiflorum Lam.) and to establish a common response coefficient c between accumulation of dry matter and plant N. Analysis of variance established the validity of this hypothesis. The model accurately described response of dry matter, plant N removal, and plant N concentration to applied N, with an overall correlation coefficient of 0.9954. Furthermore, the model closely described the relationship between yield and plant N removal, as well as between plant N concentration and plant N removal. The logistic equation is well-behaved and simple to use on a pocket calculator. It can be used to estimate yields and plant N removal in evaluation of agricultural production and environmental quality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750094
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  • 6
    Electronic Resource
    Electronic Resource
    Land application of poultry litter and water quality in Oklahoma, U.S.A. (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 165-173 
    Details
    ISSN: 1573-0867
    Keywords: Animal manure ; eutrophication ; ground water ; nitrogen ; phosphorus ; surface runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract With the rapid growth of the poultry industry in Oklahoma, U.S.A., more litter is applied to farm land. Thus, information is required on the impact of applications on regional soil and water resources. The effect of soil and poultry litter management on nitrogen (N) and phosphorus (P) loss in runoff and subsurface flow from four 16 m2 plots (Ruston fine sandy loam, 6 to 8% slope) was investigated under natural rainfall. Plots under Bermudagrass (Cynodon dactylon) received 11 Mg litter ha−1, which amounts to contributions of approximately 410 kg N and 140 kg P ha−1 yr−1. In spring, litter was broadcast on 3 of the plots; the upper half of one and total area of the other two. One of the total-area broadcast plots was tilled to 6 cm, the other remained as no till. The fourth plot served as a control. Relative to the control, litter application increased mean concentrations of total N and total P in runoff during the 16-week study for no-till (15.4 and 5.8 mg L−1) and tilled treatments (16.7 and 6.1 mg L−1). However, values for the half-area application (5.6 and 2.0 mg L−1) were similar to the control (5.7 and 1.3 mg L−1). Interflow (subsurface lateral flow at 70 cm depth) P was not affected by litter application; however, nitrate-N concentrations increased from 0.6 (control) to 2.9 mg L−1 (no till). In all cases, 〈 2 % litter N and P was lost in runoff and interflow, maintaining acceptable water quality concentrations. Although litter increased grass yield (8518 kg ha−1) compared to the control (3501 kg ha−1), yields were not affected by litter management. An 8-fold increase in the plant available P content of surface soil indicates long-term litter management and application rates will be critical to the environmentally sound use of this nutrient resource.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750462
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of nitrogen catch crop species on the nitrogen nutrition of succeeding crops (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 227-234 
    Details
    ISSN: 1573-0867
    Keywords: catch crop ; mineralization ; nitrogen ; plant species ; residual effects ; soil depletion ; winter hardiness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ten widely different plant species were compared for their ability to reduce soil mineral nitrogen levels in the autumn and their ability to improve the nitrogen nutrition of the succeeding crop. The species included monocots and dicots, crops that survived the winter (persistent) or were winter killed (non-persistent) as well as legumes and non legumes. Their ability to reduce soil mineral nitrogen content was dependent on both root depth and persistency of the crops in the autumn. For non-persistent catch crops most of the mineralization of plant nitrogen occurred during the winter, and for some of these so early as to allow leaching of some mineralized nitrogen. For persistent crops most of the mineralization occurred shortly after incorporation in the spring. The effect of the catch crops on nitrogen uptake by the succeeding barley crop varied from 13 to 66 kg N ha−1 and the differences between the crops could not be related to any single character, but to a combination of root depth, persistency, plant nitrate accumulation, and depletion of the soil mineral nitrogen pool in spring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00748941
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  • 8
    Electronic Resource
    Electronic Resource
    Linkages between organic matter mineralization and denitrification in eight riparian wetlands (1994)
    Springer
    Biogeochemistry 25 (1994), S. 19-39 
    Details
    ISSN: 1573-515X
    Keywords: denitrification ; mineralization ; nitrification ; nitrogen ; riparian ; stream ; wetland ; New Jersey ; Pennsylvania ; Pinelands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Denitrification (N2 production) and oxygen consumption rates were measured at ambient field nitrate concentrations during summer in sediments from eight wetlands (mixed hardwood swamps, cedar swamps, heath dominated shrub wetland, herbaceous peatland, and a wetland lacking live vegetation) and two streams. The study sites included wetlands in undisturbed watersheds and in watersheds with considerable agricultural and/or sewage treatment effluent input. Denitrification rates measured in intact cores of water-saturated sediment ranged from ≤ 20 to 260 μmol N m-2 h-1 among the three undisturbed wetlands and were less variable (180 to 260 μmol N M-2 h-1) among the four disturbed wetlands. Denitrification rates increased when nitrate concentrations in the overlying water were increased experimentally (1 up to 770 μM), indicating that nitrate was an important factor controlling denitrification rates. However, rates of nitrate uptake from the overlying water were not a good predictor of denitrification rates because nitrification in the sediments also supplied nitrate for denitrification. Regardless of the dominant vegetation, pH, or degree of disturbance, denitrification rates were best correlated with sediment oxygen consumption rates (r 2 = 0.912) indicating a relationship between denitrification and organic matter mineralization and/or sediment nitrification rates. Rates of denitrification in the wetland sediments were similar to those in adjacent stream sediments. Rates of denitrification in these wetlands were within the range of rates previously reported for water-saturated wetland sediments and flooded soils using whole core15N techniques that quantify coupled nitrification/denitrification, and were higher than rates reported from aerobic (non-saturated) wetland sediments using acetylene block methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00000510
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  • 9
    Electronic Resource
    Electronic Resource
    Assessment of nutrient availability and limitation using macroalgae (1994)
    Springer
    Journal of aquatic ecosystem stress and recovery 3 (1994), S. 27-34 
    Details
    ISSN: 1573-5141
    Keywords: nutrient limitation ; critical tissue concentrations ; nitrogen ; phosphorus ; macroalgae ; biomonitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Discs of the macroalga,Ulva lactuca L., were transplanted around an ocean outfall and at a reference site in Køge Bay, Denmark, to assess the influence of the outfall on the nutrient availability. At 2-wk intervals, samples were collected and analyzed for growth, nitrogen, and phosphorus content. The tissue concentrations of nitrogen and phosphorus decreased with distance to the outfall, showing that the tissue concentrations are suitable for monitoring nutrient availability in coastal areas and provide a time-integrated measure of the nutrient availability. The lowest tissue concentrations of nitrogen were recorded at the reference station, where the internal concentrations generally were below the critical concentration level, showing that nitrogen limited the growth. At the station located close to the outfall, the flux of nitrogen was sufficient to maintain the maximum growth rate. The tissue concentrations of phosphorus were only below the critical concentration level on one occasion, and the result showed a net uptake throughout the study period. It was concluded that in the Køge Bay, nitrogen was the main limiting factor for macroalgae growth during the summer. The applicability of tissue concentrations for assessment of nutrient availability is discussed and it is considered that the method, when evaluated against established critical concentrations, provides a valuable tool for assessing ecosystem health with regard to eutrophication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00045154
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  • 10
    Electronic Resource
    Electronic Resource
    Mycorrhizal dependency of micropropagated argan tree (Argania spinosa): II. Mineral nutrition (1994)
    Springer
    Agroforestry systems 27 (1994), S. 67-77 
    Details
    ISSN: 1572-9680
    Keywords: Argania spinosa ; micro-elements ; nitrogen ; phosphorus ; V.A. mycorrhization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé L'influence de la mycorhization V.A. sur la nutrition minérale de 2 clones d'Arganier (Argania spinosa) a été étudiée sur des plantules micropropagées in vitro poussant en conditions contrôlées. L'inoculation (qui augmentait la production de matière sèche d'un facteur 4,5) accroit également la teneur des plantes en phosphore, notamment dans les feuilles, et les plantes mycorhizées mobilisent 15 fois plus de phosphore que les plantes non inoculées. La teneur en azote est légèrement plus faible chez les plantes mycorhizées mais au total ces dernières exportent 3 fois plus d'azote. L'absorption des micro-éléments est aussi affectée par l'inoculation, qui accroit les teneurs des plantes en Fe, Zn et Cu. La nutrition minérale des deux clones étudiés semble affectée par le rapport racines/parties aériennes et d'autres caractéristiques génétiques, comme l'efficacité de translocation du fer. Ces résultats nous permettent de comprendre en quoi son système racinaire profond et mycorhizé permet à l'Arganier non seulement de pousser dans des zones arides aux sols pauvres, mais aussi d'améliorer la fertilité des couches supérieures du sol par l'effet litière.
    Notes: Abstract The influence of V.A. mycorrhization on mineral nutrition of 2 clones ofArgania spinosa was studied with in-vitro micropropagated plantlets grown in confined medium under controlled conditions. Inoculation, which increased dry matter production by a factor of 4.5, also increased P concentration in the plant, especially in the leaves, and the mycorrhizal plants mobilized 15 times more P than control plants. N concentration was slightly lower in mycorrhizal plants, but total N content was 3 times higher. Uptake of micro elements was also affected, inoculation increasing plant Fe, Zn and Cu content. Mineral nutrition in the test clones seemed affected by root/shoot ratio and other genetically-related characteristics, such as Fe translocation efficiency. These results help us to understand how its deep mycorrhizal root system might allowArgania spinosa not only to grow in infertile arid areas but also to improve top-soil fertility by a litter effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00704835
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  • 11
    Electronic Resource
    Electronic Resource
    Regulatory circuits of theamdS gene ofAspergillus nidulans (1994)
    Springer
    Antonie van Leeuwenhoek 65 (1994), S. 179-182 
    Details
    ISSN: 1572-9699
    Keywords: Aspergillus ; fungus ; catabolism ; activation ; repression ; nitrogen ; carbon ; zinc fingers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheamdS gene codes for an acetamidase enzyme that hydrolyses acetamide to acetate and ammonium thus providingA. nidulans with a source of carbon and nitrogen. The exceptionally favourable genetics of this system combined with molecular analysis have enabled many regulatory circuits affectingamdS to be identified genetically. Characterization of the regulatory genes and the definition of the cis-acting sites involved have been done using bothin vivo andin vitro mutagenesis. Recent results on the analysis of the system are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00871944
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  • 12
    Electronic Resource
    Electronic Resource
    Vapor-liquid equilibria for the ternary system N2 + CO2 +n-C4H10 at 250 and 270 K1 (1994)
    Springer
    International journal of thermophysics 15 (1994), S. 1211-1219 
    Details
    ISSN: 1572-9567
    Keywords: binary system ; butane ; carbon dioxide ; nitrogen ; ternary system ; vapor-liquid equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The system studied was nitrogen + carbon dioxide +n-butane at 250 and 270 K and at pressures from 1.5 to 14 MPa. The Peng-Robinson equation was used to model the results, since it is the most widely accepted equation of state in the gas processing industry. In general, the predictions are most accurate at low and moderate pressures and poorest at high pressures, especially near the critical region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01458829
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  • 13
    Electronic Resource
    Electronic Resource
    Photoautotrophic growth of soybean cells in suspension culture III. Characterization of carbon fixation products under high and low CO2 levels (1994)
    Springer
    Plant cell, tissue and organ culture 39 (1994), S. 239-244 
    Details
    ISSN: 1573-5044
    Keywords: carbon ; elevated CO2 ; nitrogen ; suspension culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A photoautotrophic soybean suspension culture (SB-P) was used to study CO2 assimilation while exposed to elevated or ambient CO2 levels. These studies showed that under elevated CO2 (5% v/v) malate is the dominant fixation product, strongly suggesting that phosphoenolpyruvate carboxylase (PEPCase) is the primary enzyme involved in carbon fixation in these cells under their normal growth conditions. Citrate and [aspartate + glutamate] were also significant fixation products during fifteen minutes of exposure to 14CO2. During the ten minute unlabeled CO2 chase however, 14C-malate continued to increase while citrate and [aspartate + glutamate] declined. Fixation of 14CO2 under ambient CO2 levels (0.037%) showed a very different product pattern as 3-phosphoglycerate was very high in the first one to two minutes followed by increases in [serine + glycine] and [aspartate + glutamate]. Hexose phosphates were also quite high initially but then declined relatively rapidly. Thus, the carbon fixation pattern at ambient CO2 levels resembles somewhat that seen in C3 leaf cells while that seen at elevated CO2 levels more closely resembles that of a C4 plant. The initial fixation product of C3 plants, 3-PGA, was never detectable under high CO2 conditions. These data suggest that an in vitro photoautotrophic system would be suitable for studying carbon fixation physiology during photosynthetic and non-photosynthetic growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00035976
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  • 14
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    Scion-rootstock relationships with respect to height growth and foliar concentrations of nitrogen and phosphorus in reciprocal grafts of Pinus caribaea var. hondurensis (1994)
    Springer
    New forests 8 (1994), S. 71-79 
    Details
    ISSN: 1573-5095
    Keywords: foliage ; grafting ; nitrogen ; phosphorus ; Pinus caribaea ; rootstock ; scion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Both scion and rootstock clones significantly influenced scion elongation and concentrations of nitrogen and phosphorus in the scion foliage. Scion clone was the more important determinant. Scion clone × rootstock clone interactions were not significant. The ability of a clone to elongate as a scion was not correlated with its capacity to promote or retard scion elongation when used as a rootstock. Genetic differences in foliar nutrient concentrations appeared to reflect levels of nutrient demand, rather than the ability of roots to absorb nutrients. Nutrient demand of the rootstock can also explain negative correlations between nitrogen levels in rootstock clones and levels of both nitrogen and phosphorus in the scions. There was no significant relationship between scion elongation and foliar nitrogen concentrations of either rootstock or scion. The weak relationship between scion elongation and concentration of phosphorus in the rootstock apparently resulted from tissue dilution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00034132
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  • 15
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    Short-term studies of 15NO3 - and 15NH4 + uptake by micropropagated strawberry shoots cultured with or without CO2 enrichment (1994)
    Springer
    Plant cell, tissue and organ culture 37 (1994), S. 185-191 
    Details
    ISSN: 1573-5044
    Keywords: Fragaria x ananassa ; in vitro ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The uptake of 15NO3 - and 15NH4 + has been examined in 5-,10- and 28-day-old micropropagated strawberry (Fragaria x ananassa Duch. cv. Kent) shoots rooted in one-half strength Murashige and Skoog (MS) liquid medium on cellulose plugs (Sorbarods). The results indicated that the plantlets absorbed both NO3 - and NH4 + during the culture with a greater uptake of NH4 + at 5 days of culture. Furthermore, a pronounced reduction in NO3 - and NH4 + uptake at 10 and 28 days of culture was observed within 6 h of the short-term uptake study. This reduction could be explained by the low CO2 concentration in test tubes during the photoperiod, since no reduction in nitrogen uptake occurred in the CO2 enriched condition. The results are interpreted as an indication of the important role for photosynthetic CO2 fixation in the process of nitrogen uptake by the plantlets during the rooting stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043614
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  • 16
    Electronic Resource
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    Effect of nitrogen and sucrose on the primary and secondary metabolism of transformed root cultures of Hyoscyamus muticus (1994)
    Springer
    Plant cell, tissue and organ culture 38 (1994), S. 263-272 
    Details
    ISSN: 1573-5044
    Keywords: Fatty acids ; hyoscyamine ; Hyoscyamus muticus ; nitrogen ; sucrose ; transformed root cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abatract The effect of carbon and nitrogen sources on two well-established hairy root clones, LBA1S and C58A, of Hyoscyamus muticus strain Cairo, were investigated. Both clones exhibited completely different patterns with regards to their growth rate, hyoscyamine accumulation, and fatty acid contents. Clone C58A grew faster and yielded more biomass (17.4 g l-1, in 21 days), but produced less hyoscyamine. The maximum hyoscyamine content (120 mg l-1) in clone LBA1S was reached in 28 days. Neither of the clones could use lactose or fructose as the sole carbon source, nor ammonium as the sole nitrogen source. The growth in the medium containing glucose was significantly reduced compared to that containing sucrose. Clone LBA1S was sensitive to the changes in sucrose concentration and an increase in ammonium in the culture medium, whereas C58A tolerated these changes better but was more sensitive to the increase in total nitrogen. Lipid synthesis was active in the exponential growth phase, and the total fatty acid content varied from 5 to 34 mg g-1 of dry root material. The major fatty acids were linoleic, palmitic and linolenic. There were considerable differences in the total amount of lipids and in their relative ratios when different nutrients were applied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00033886
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  • 17
    Electronic Resource
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    Growth and elemental content of several sagebrush-steppe species in unburned and post-wildfire soil and plant effects on soil attributes (1994)
    Springer
    Plant and soil 164 (1994), S. 35-41 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; phosphorus ; revegetation ; silica ; succession ; shrubland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fire is the principal means of stand renewal in big sagebrush-steppe communities of western North America. Plant growth following fire may be influenced by heat-induced changes in the nutrient status of the soil. Moreover, post-wildfire pioneer plant species may alter soil properties, and thereby, impact subsequent plant recruitment. Our study compared the growth and elemental content of big sagebrush (Artemisia tridentata), squirreltail (Elymus elymoides), cheatgrass (Bromus tectorum), and Indian ricegrass (Achnatherum hymenoides), grown under greenhouse conditions in post-wildfire and similar unburned soil. We also examined soil attributes following plant growth. Cheatgrass and squirreltail, grown in post-wildfire soil, had significantly (p≤0.05) greater aboveground mass than plants grown in unburned soil. As compared with unburned soil, post-wildfire soil engendered the following significant (p≤0.05) differences in leaf elemental content: 1) big sagebrush had higher levels of P and lower levels of Mn; 2) squirreltail accumulated more P and N; and 3) all grass species had higher SiO2 content. Following harvest of plants, post-wildfire soil generally contained significantly (p≤0.05) more KCl-extractable ortho-P, NH inf4 + , and SO 4 − , than unburned soil. Plant growth in both burned and unburned soils fostered a significant (p≤0.05) increase in the bicarbonate-extractable pool of P as compared with unplanted controls. Soil Kjeldahl-N was significantly (p≤0.05) greater after plant growth in burned treatments as compared with the control. This study demonstrates that post-wildfire soil can have a stimulatory effect on plant growth for some species. Squirreltail deserves consideration as a post-wildfire revegetation species. Furthermore, pioneer plant growth following wildfires can attenuate soil properties and therefore influence plant succession.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010108
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  • 18
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    Mineralization of carbon and nitrogen in acid forest soil treated with fast and slow-release nutrients (1994)
    Springer
    Plant and soil 164 (1994), S. 187-193 
    Details
    ISSN: 1573-5036
    Keywords: apatite ; biotite ; forest soil ; mineralization ; nitrogen ; nutrient additions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of slow (apatite, biotite) and fast-release nutrients (P, K, Mg) on C and N mineralization in acid forest soil were studied. These nutrients were applied alone or together with urea or urea and limestone. The production of CO2 in the soil samples taken one and three growing seasons after the application was lower in the soils treated with the fast-release nutrients than in the untreated soils. Similar reduction of microbial activity was not seen after the apatite and apatite+biotite treatments. In the first growing season, urea and urea+limestone enhanced CO2 production, but after three growing seasons, the opposite was true. Apatite and apatite+biotite added together with urea did not compensate for the decreasing effect of urea on the CO2 production. The addition of fast-release salts increased somewhat the concentration of NH inf4 sup+ in the soil and more NH4 + accumulated during laboratory incubation in the soil samples taken one growing season after the application. The urea addition immediately increased the concentrations of NH4 + and of NO3 − in the soil, but, three growing seasons after application, urea had only a slight increasing effect on mineral N content of the soil. Slow-release nutrients seem to have a more favourable effect than fast-release salts on nutrient turnover in acid forest soil.
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    URL: http://dx.doi.org/10.1007/BF00010070
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  • 19
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    Isotope ratios and concentrations of sulfur and nitrogen in needles and soils of Picea abies stands as influenced by atmospheric deposition of sulfur and nitrogen compounds (1994)
    Springer
    Plant and soil 164 (1994), S. 267-281 
    Details
    ISSN: 1573-5036
    Keywords: atmospheric deposition ; δ15N ; δ34S ; forest decline ; nitrogen ; Picea abies ; stable isotopes ; sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Concentrations and natural isotope abundance of total sulfur and nitrogen as well as sulfate and nitrate concentrations were measured in needles of different age classes and in soil samples of different horizons from a healthy and a declining Norway spruce (Picea abies (L.) Karst.) forest in the Fichtelgebirge (NE Bavaria, Germany), in order to study the fate of atmospheric depositions of sulfur and nitrogen compounds. The mean δ15N of the needles ranged between −3.7 and −2.1 ‰ and for δ34S a range between −0.4 and +0.9 ‰ was observed. δ34S and sulfur concentrations in the needles of both stands increased continuously with needle age and thus, were closely correlated. The δ15N values of the needles showed an initial decrease followed by an increase with needle age. The healthy stand showed more negative δ15N values in old needles than the declining stand. Nitrogen concentrations decreased with needle age. For soil samples at both sites the mean δ15N and δ34S values increased from −3 ‰ (δ15N) or +0.9 ‰ (δ34S) in the uppermost organic layer to about +4 ‰ (δ15N) or +4.5 ‰ (δ34S) in the mineral soil. This depth-dependent increase in abundance of 15N and 34S was accompanied by a decrease in total nitrogen and sulfur concentrations in the soil. δ15N values and nitrogen concentrations were closely correlated (slope −0.0061 ‰ δ15N per μmol eq N gdw −1), and δ34S values were linearly correlated with sulfur concentrations (slope −0.0576 ‰ δ34S per μmol eq S gdw −1). It follows that in the same soil samples sulfur concentrations were linearly correlated with the nitrogen concentrations (slope 0.0527), and δ34S values were linearly correlated with δ15N values (slope 0.459). A correlation of the sulfur and nitrogen isotope abundances on a Δ basis (which considers the different relative frequencies of 15N and 34S), however, revealed an isotope fractionation that was higher by a factor of 5 for sulfur than for nitrogen (slope 5.292). These correlations indicate a long term synchronous mineralization of organic nitrogen and sulfur compounds in the soil accompanied by element-specific isotope fractionations. Based on different sulfur isotope abundance of the soil (δ34S=0.9 ‰ for total sulfur of the organic layer was assumed to be equivalent to about −1.0 ‰ for soil sulfate) and of the atmospheric SO2 deposition (δ34S=2.0 ‰ at the healthy site and 2.3 ‰ at the declining site) the contribution of atmospheric SO2 to total sulfur of the needles was estimated. This contribution increased from about 20 % in current-year needles to more than 50 % in 3-year-old needles. The proportion of sulfur from atmospheric deposition was equivalent to the age dependent sulfate accumulation in the needles. In contrast to the accumulation of atmospheric sulfur compounds nitrogen compounds from atmospheric deposition were metabolized and were used for growth. The implications of both responses to atmospheric deposition are discussed.
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    URL: http://dx.doi.org/10.1007/BF00010079
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  • 20
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    Nitrogen mineralization and H+ transfers in a Scots pine (Pinus sylvestris L.) forest soil as affected by liming (1994)
    Springer
    Plant and soil 161 (1994), S. 209-218 
    Details
    ISSN: 1573-5036
    Keywords: ammonification ; H+ production ; in-situ incubation ; liming ; mineralization ; nitrification ; nitrogen ; Pinus sylvestris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract H+ production due to N uptake in a mature Scots pine stand subjected to high NH4 + deposition was previously estimated to amount to approx. 2.2 kmol ha-1 y-1. The question whether H+ transfers related to N mineralization (ammonification and nitrification) offset or corroborate this proton production is investigated in the present research. To determine N mineralization, soil cores were used of which both ends were closed with layers of ion exchange resin (IER) to prevent influx and efflux of ions. The effect of liming on N mineralization and the resulting H+ production was investigated in 7 incubation periods of each ca. 8 wk. Because of its high mobility NO3 accumulated in both IER layers at the expense of that in the incubated forest floor and mineral soil. Net N mineralization in the soil cores as a whole amounted to 40 and 77 kg N ha-1 in 384 d in the control and limed plots, respectively. In both treatments ca. 65% of mineralized N was nitrified. H+ production due to N mineralization amounted to approx. 1.2 kmol ha-1 y-1 in the control and limed plots. Liming reduced the amount of C in the forest floor, but not forest floor mass, because of an increased mixing with mineral particles.
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    URL: http://dx.doi.org/10.1007/BF00046391
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  • 21
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    Soil pCO2, soil respiration, and root activity in CO2-fumigated and nitrogen-fertilized ponderosa pine (1994)
    Springer
    Plant and soil 165 (1994), S. 129-138 
    Details
    ISSN: 1573-5036
    Keywords: carbon dioxide ; nitrogen ; ponderosa pine ; soil respiration ; soil carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The purpose of this paper is to describe the effects of CO2 and N treatments on soil pCO2, calculated CO2 efflux, root biomass and soil carbon in open-top chambers planted with Pinus ponderosa seedlings. Based upon the literature, it was hypothesized that both elevated CO2 and N would cause increased root biomass which would in turn cause increases in both total soil CO2 efflux and microbial respiration. This hypothesis was only supported in part: both CO2 and N treatments caused significant increases in root biomass, soil pCO2, and calculated CO2 efflux, but there were no differences in soil microbial respiration measured in the laboratory. Both correlative and quantitative comparisons of CO2 efflux rates indicated that microbial respiration contributes little to total soil CO2 efflux in the field. Measurements of soil pCO2 and calculated CO2 efflux provided inexpensive, non-invasive, and relatively sensitive indices of belowground response to CO2 and N treatments.
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    URL: http://dx.doi.org/10.1007/BF00009969
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  • 22
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    Enhanced root system C-sink activity, water relations and aspects of nutrient acquisition in mycotrophic Bouteloua gracilis subjected to CO2 enrichment (1994)
    Springer
    Plant and soil 165 (1994), S. 139-146 
    Details
    ISSN: 1573-5036
    Keywords: blue grama ; Bouteloua gracilis ; C4 grass ; CO2 enrichment ; mycorrhizae ; nitrogen ; phosphorus ; VAM ; water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to better elucidate fixed-C partitioning, nutrient acquisition and water relations of prairie grasses under elevated [CO2], we grew the C4 grass Bouteloua gracilis (H.B.K.) lag ex Steud. from seed in soil-packed, column-lysimeters in two growth chambers maintained at current ambient [CO2] (350 μL L−1) and twice enriched [CO2] (700 μL L−1). Once established, plants were deficit irrigated; growth chamber conditions were maintained at day/night temperatures of 25/16°C, relative humidities of 35%/90% and a 14-hour photoperiod to simulate summer conditions on the shortgrass steppe in eastern Colorado. After 11 weeks of growth, plants grown under CO2 enrichment had produced 35% and 65% greater total and root biomass, respectively, and had twice the level of vesicular-arbuscular mycorrhizal (VAM) infection (19.8% versus 10.8%) as plants grown under current ambient [CO2]. The CO2-enriched plants also exhibited greater leaf water potentials and higher plant water use efficiencies. Plant N uptake was reduced by CO2 enrichment, while P uptake appeared little influenced by CO2 regime. Under the conditions of the experiment, CO2 enrichment increased root biomass and VAM infection via stimulated growth and adjustments in C partitioning below-ground.
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    URL: http://dx.doi.org/10.1007/BF00009970
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  • 23
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    Root architectural responses of Betula lenta to spatially heterogeneous ammonium and nitrate (1994)
    Springer
    Plant and soil 158 (1994), S. 129-134 
    Details
    ISSN: 1573-5036
    Keywords: Betula lenta L. ; black birch ; nitrogen ; root architecture ; soil heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inorganic soil nitrogen is often heterogeneously distributed, both spatially and in form (ammonium versus nitrate). Here we present information on the architecture of black birch (Betula lenta L.) root systems exposed to homogeneous and heterogeneous nitrogen environments. The major effects on root architecture were at the whole root system level in response to heterogeneity of nitrogen form rather than the effect of local of local nitrate or ammonium supply on local root growth. In the heterogeneous treatment, plant root systems had greater link lengths and more simple branching patterns. Root architectural responses to heterogeneous nitrogen, independent of localized responses to patches, suggest that in a seedling of B. lenta whole plant integration of its environment may override local control of root growth.
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    URL: http://dx.doi.org/10.1007/BF00007925
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  • 24
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    Influence of nitrogen, plant growth stage, and environment on charcoal rot of grain sorghum caused by Macrophomina phaseolina (Tassi) Goid (1994)
    Springer
    Plant and soil 158 (1994), S. 203-210 
    Details
    ISSN: 1573-5036
    Keywords: charcoal rot ; Macrophomina phaseolina ; nitrogen ; NH4NO3 ; Sorghum bicolor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Colonization of sorghum by Macrophomina phaseolina in field plots was determined at nitrogen fertilization rates of 0, 56, 112, and 168 kg ha-1 in 1988 and 0, 84, 168, and 256 kg ha-1 in 1989. Above ground plant tissue and roots were sampled monthly to determine total nitrogen and percent colonization of root segments by natural inoculum. Root infection was not affected by nitrogen treatment, but was affected by growth stage and environment. High root infection occurred before reproductive development (growth stage 3) in 1988 and was associated with hot, dry weather early in the growing season. In 1989, when the weather was cool and wet, root infection began after reproductive development (growth stage 4). The effect of nitrogen treatments on lesion length was determined in sorghum stalks artificially inoculated with M. phaseolina. Lesion lengths were significantly affected by both nitrogen treatments and growth stage. Lesions were significantly longer with all nitrogen treatments at growth stage 9 than with the no-nitrogen treatment, and lesions tended to increase with increased levels of nitrogen fertilization. Significant increases in lesion length occurred between growth stages 5, 7, and 9 in 1988 and between 7 and 9 in 1989. This study demonstrates that nitrogen fertilization affects colonization of sorghum stalks but not root infection by M. phaseolina.
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    URL: http://dx.doi.org/10.1007/BF00009495
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  • 25
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    Root growth and nitrogen uptake in sycamore (Acer pseudoplantanus L.) seedlings in relation to nitrogen supply (1994)
    Springer
    Plant and soil 158 (1994), S. 233-238 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; precoditioning ; roots ; sycamore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Acer pseudoplatanus L. trees were grown in sand culture for 2 years and, in 1988, supplied with either 1.0 mol N m-3 (low N) or 6.0 mol N m-3 (high N) to precondition their growth. In 1989, the same trees received either high or low nitrogen, producing four treatments; High N in 1988/High N in 1989; High N in 1988/Low N in 1989; Low N in 1988/Low N in 1989; and Low N in 1988/High N in 1989. Plant growth was affected by N supply in both years. In 1989 the Low N/High N treated trees had the same overall mass, leaf mass and stem girth as the High N/High N treatment. Early spring growth of foliage and roots was conditional on nitrogen supplied in the previous season. Later, the rapid increases in leaf, stem and root growth under high N was through root uptake. Internal partitioning of growth was affected, with the Low N/High N treatment producing more new leaves on axillary shoots, and more new white roots on existing structures, than the Low N/Low N treatment. Despite effects of the N preconditioning on the structure of both canopy and root system, nitrogen uptake was solely dependent on the current nitrogen supply.
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    URL: http://dx.doi.org/10.1007/BF00009498
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  • 26
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    Triphenyltetrazolium chloride as an indicator of fine-root vitality and environmental stress in coniferous forest stands: Applications and limitations (1994)
    Springer
    Plant and soil 159 (1994), S. 297-300 
    Details
    ISSN: 1573-5036
    Keywords: enzymes ; fine root vitality ; nitrogen ; Picea abies ; Pinus sylvestris ; triphenyltetrazolium chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The present study is an attempt to investigate whether triphenyltetrazolium chloride (TTC), a chemical compound which measures dehydrogenase activity, could be used to study fine-root vitality from two different points of view: (i) in relation to ageing; (ii) as an indicator of environmental stress, in this case of excess nitrogen. The study was performed with excavated fine-roots from middle-aged Norway spruce and Scots pine stands. The ageing aspect was investigated by applying TTC to fine roots separated into different vitality classes, based on certain morphological characteristics. A significant difference in activity was demonstrated only in the case of roots that could be referred to as living and dead, respectively. The use of TTC on fine roots grown at different nitrogen supply levels indicates a possible increase in dehydrogenase activity with increasing nitrogen supply.
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    URL: http://dx.doi.org/10.1007/BF00009293
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  • 27
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    Nutrient uptake in eastern deciduous tree seedlings (1994)
    Springer
    Plant and soil 160 (1994), S. 193-199 
    Details
    ISSN: 1573-5036
    Keywords: gaps ; ion uptake ; nitrogen ; nutrient acquisition ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tree seedlings that colonize large treefall gaps are generally shade-intolerant species with high potential relative growth rates. Nutrient availability may be significantly elevated in disturbance-induced gaps, however, little is known about the role of differences in nutrient uptake capacities of different species in structuring the community response to gap openings in eastern North American deciduous forests. Seven tree species were grown from seed under both a high and a low nutrient regime, and uptake kinetics of phosphate, ammonium, and nitrate were studied. Yellow birch, a species with intermediate shade tolerance and relative growth rate, had the highest maximum rates of uptake of all ions, while tulip tree, a gap-colonizing species with high relative growth rate, had the lowest rate of phosphate uptake and intermediate rates of ammonium and nitrate uptake. Beech and hickory, which have low relative growth rates and are not gap-colonizing species, had intermediate levels of nutrient uptake. There was no evidence that species with the highest maximum uptake rates measured at high supply concentrations had relatively low uptake at low nutrient supply concentrations. Although birch increased phosphate absorption capacity when grown under a low nutrient regime, this pattern did not hold for nitrate or ammonium uptake, and other species showed no change in nutrient uptake capacity according to nutrient growth regime. Clearly, factors other than nutrient absorption capacity, such as nutrient use efficiency or allocation to root vs. shoot biomass, underlie differences in species' capacities to colonize and maintain a high relative growth rate in canopy gaps.
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    URL: http://dx.doi.org/10.1007/BF00010145
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  • 28
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    A simple model for estimating the contribution of nitrogen mineralization to the nitrogen supply of crops from a stabilized pool of soil organic matter and recent organic input (1994)
    Springer
    Plant and soil 162 (1994), S. 259-271 
    Details
    ISSN: 1573-5036
    Keywords: mineralization rate ; nitrogen ; stabilized organic matter ; crop rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A simple model was developed to estimate the contribution of nitrogen (N) mineralization to the N supply of crops. In this model the soil organic matter is divided into active and passive pools. Annual soil mineralization of N is derived from the active pool. The active pool comprises stabilized and labile soil organic N. The stabilized N is built up from accumulated inputs of fresh organic N during a crop rotation but the labile N is a fraction of total N added, which mineralizes faster than the stabilized N. The passive pool is considered to have no participation in the mineralization process. Mineralization rates of labile and stabilized soil organic N from different crop residues decomposing in soil were derived from the literature and were described by the first-order rate equation dN/dt =-K*N, where N is the mineralizable organic N from crop residues andK is a constant. The data were groupedK 1 by short-term (0–1 year) andK 2 by long-term (0–10 years) incubation. Because the range of variation inK 2 was smaller than inK 1 we felt justified in using an average value to derive N mineralization from the stabilized pool. The use of a constant rate ofK 1 was avoided so net N mineralization during the first year after addition is derived directly from the labile N in the crop residues. The model was applied to four Chilean agro-ecosystems, using daily averages of soil temperature and moisture. The N losses by leaching were also calculated. The N mineralization varied between 30 and 130 kg N ha−1 yr−1 depending on organic N inputs. Nitrogen losses by leaching in a poorly structured soil were estimated to be about 10% of total N mineralized. The model could explain the large differences in N- mineralization as measured by the potential N mineralization at the four sites studied. However, when grassland was present in the crop rotation, the model underestimated the results obtained from potential mineralization.
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    URL: http://dx.doi.org/10.1007/BF01347713
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  • 29
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    Decomposition of tree leaf litters grown under elevated CO2: Effect of litter quality (1994)
    Springer
    Plant and soil 163 (1994), S. 121-130 
    Details
    ISSN: 1573-5036
    Keywords: decomposition rates ; enriched CO2 ; lignin ; litter respiration ; microcosms ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ash (Fraxinus excelsior L.), birch (Betula pubescens Ehrh.), sycamore (Acer pseudoplatanus L.) and Sitka spruce (Picea sitchensis (Bong.) Carr.) leaf litters were monitored for decomposition rates and nutrient release in a laboratory microcosm experiment. Litters were derived from solar domes where plants had been exposed to two different CO2 regimes: ambient (350 μL L-1 CO2) and enriched (600 μL L-1 CO2). Elevated CO2 significantly affected some of the major litter quality parameters, with lower N, higher lignin concentrations and higher ratios of C/N and lignin/N for litters derived from enriched CO2. Respiration rates of the deciduous species were significantly decreased for litters grown under elevated CO2, and reductions in mass loss at the end of the experiment were generally observed in litters derived from the 600 ppm CO2 treatment. Nutrient mineralization, dissolved organic carbon, and pH in microcosm leachates did not differ significantly between the two CO2 treatments for any of the species studied. Litter quality parameters were examined for correlations with cumulative respiration and decomposition rates: N concentration, C/N and lignin/N ratios showed the highest correlations, with differences between litter types. The results indicate that higher C storage will occur in soil as a consequence of litter quality changes resulting from higher atmospheric concentrations of CO2.
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    URL: http://dx.doi.org/10.1007/BF00033948
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  • 30
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    Effects of ammonium sulphate application on the rhizosphere, fine-root and needle chemistry in aPicea abies (L.) Karst. stand (1994)
    Springer
    Plant and soil 162 (1994), S. 71-80 
    Details
    ISSN: 1573-5036
    Keywords: ammonium sulphate ; fine roots ; needles ; nitrogen ; Norway spruce ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rhizosphere, fine-root and needle chemistry were investigated in a 28 year old Norway spruce stand in SW Sweden. The uptake and allocation pattern of plant nutrients and aluminium in control plots (C) and plots repeatedly treated with ammonium sulphate (NS) were compared. Treatments started in 1988. Current year needles, one-year-old needles and cylindrical core samples of the LFH-layer and the mineral soil layers were sampled in 1988, 1989 and 1990. Compared to the control plots, pH decreased significantly in the rhizosphere soil in the NS plots in 1989 and 1990 while the SO4-S concentration increased significantly. Aluminium concentration in the rhizosphere soil was generally higher in the NS plots in all soil layers, except at 0–10 cm depths, both in 1989 and 1990. Calcium, Mg and K concentrations also increased after treatment with ammonium sulphate. Ammonium ions may have replaced these elements in the soil organic matter. The NS treatment significantly reduced Mg concentrations in fine roots in all layers in 1990. A similar trend was found in the needles. Ca concentrations in fine roots were significantly lower in the NS plots in the LFH layer in 1990 and the same pattern was found in the current needles. The N and S concentrations of both fine roots and needles were significantly higher in the NS plots. It was suggested that NS treatment resulted in displacement of Mg, Ca and K from exchange sites in the LFH layer leading to leaching of these cations to the mineral soil. Further application of ammonium sulphate may damage the fine roots and consequently adversely affect the water and nutrient uptake of root systems.
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    URL: http://dx.doi.org/10.1007/BF01416091
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    Root response to CO2 enrichment and nitrogen supply in loblolly pine (1994)
    Springer
    Plant and soil 165 (1994), S. 21-32 
    Details
    ISSN: 1573-5036
    Keywords: allocation ; CO2 ; image analysis ; loblolly pine ; nitrogen ; root morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper examines how elevated CO2 and nitrogen (N) supply affect plant characteristics of loblolly pine (Pinus taeda L.) with an emphasis on root morphology. Seedlings were grown in greenhouses from seeds during one growing season at two atmospheric CO2 concentrations (375 and 710 μL L-1) and two N levels (High and Low). Root morphological characteristics were determined using a scanner and an image analysis program on a Macintosh computer. In the high N treatment, elevated CO2 increased total plant dry weight by 80% and did not modify root to shoot (R/S) dry weight ratio, and leaf and plant N concentration at the end of the growing season. In the low N treatment, elevated CO2 increased total dry weight by 60%. Plant and leaf N concentration declined and R/S ratio tended to increase. Nitrogen uptake rate on both a root length and a root dry weight basis was greater at elevated CO2 in the high N treatment and lower in the low N treatment. We argue that N stress resulting from short exposures to nutrients might help explain the lower N concentrations observed at high CO2 in other experiments; Nitrogen and CO2 levels modified root morphology. High N increased the number of secondary lateral roots per length of first order lateral root and high CO2 increased the length of secondary lateral roots per length of first order lateral root. Number and length of first order lateral roots were not modified by either treatment. Specific root length of main axis, and to a lower degree, of first order laterals, declined at high CO2, especially at high N. Basal stem diameter and first order root diameters increased at high CO2, especially at high N. Elevated CO2 increased the proportion of upper lateral roots within the root system.
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    URL: http://dx.doi.org/10.1007/BF00009959
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  • 32
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    Above- and belowground response of Populus grandidentata to elevated atmospheric CO2 and soil N availability (1994)
    Springer
    Plant and soil 165 (1994), S. 45-51 
    Details
    ISSN: 1573-5036
    Keywords: CO2 ; gas exchange ; nitrogen ; Populus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil N availability may play an important role in regulating the long-term responses of plants to rising atmospheric CO2 partial pressure. To further examine the linkage between above- and belowground C and N cycles at elevated CO2, we grew clonally propagated cuttings of Populus grandidentata in the field at ambient and twice ambient CO2 in open bottom root boxes filled with organic matter poor native soil. Nitrogen was added to all root boxes at a rate equivalent to net N mineralization in local dry oak forests. Nitrogen added during August was enriched with 15N to trace the flux of N within the plant-soil system. Above-and belowground growth, CO2 assimilation, and leaf N content were measured non-destructively over 142 d. After final destructive harvest, roots, stems, and leaves were analyzed for total N and 15N. There was no CO2 treatment effect on leaf area, root length, or net assimilation prior to the completion of N addition. Following the N addition, leaf N content increased in both CO2 treatments, but net assimilation showed a sustained increase only in elevated CO2 grown plants. Root relative extension rate was greater at elevated CO2, both before and after the N addition. Although final root biomass was greater at elevated CO2, there was no CO2 effect on plant N uptake or allocation. While low soil N availability severely inhibited CO2 responses, high CO2 grown plants were more responsive to N. This differential behavior must be considered in light of the temporal and spatial heterogeneity of soil resources, particularly N which often limits plant growth in temperate forests.
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    URL: http://dx.doi.org/10.1007/BF00009961
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  • 33
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    Nutrient balances and phytoplankton dynamics in two agriculturally loaded shallow lakes (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 359-369 
    Details
    ISSN: 1573-5117
    Keywords: agriculture ; blue-green algae ; eutrophication ; internal loading ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The impact of agriculture was estimated on two shallow, eutrophic lakes, Lake Kotojärvi and Lake Villikkalanjärvi in southern Finland. The main emphasis was on phosphorus and nitrogen budgets and on the phytoplankton dynamics. Special attention was paid to internal P loading and blue-green algal blooms. The mean Tot-P load from agricultural land was 1.2 kg ha-1 a-1 in both basins and Tot-N loads were 19 kg ha-1 a-1 in L. Villikkalanjärvi and 12 kg ha-1 a-1 in L. Kotojärvi. The Tot-P input to L. Kotojärvi was on an average 0.62 g m-2 a-1 (per lake surface area), and the Tot-N input 9.1 g m-2 a-1. The corresponding inputs to L. Villikkalanjärvi were 3.1 and 57 g m-2 a-1, respectively. The annual variation followed the runoff volumes. About half of the Tot-P and one third of the Tot-N load was retained in L. Kotojärvi. In L. Villikkalanjärvi the retention was only 24% for Tot-P and 19% for Tot-N. The difference was very probably due to a longer theoretical retention time in L. Kotojärvi. In L. Villikkalanjärvi the mean concentration of Tot-P was 120 µg 1-1 and that of Tot-N 1700 µg 1-1 and the corresponding figures in L. Kotojärvi 67 and 990 µg 1-1, respectively. The mean chlorophyll a concentration was, however, higher in L. Kotojärvi (26 µg 1-1) than in L. Villikkalanjärvi (20 µg 1-1). This was probably due to an internal P load in L. Kotojärvi: in 1988 the internal load of dissolved P was estimated to be as much as twofold the external load. In L. Villikkalanjärvi the internal dissolved P load was only up to 50% of the external input. In L. Kotojärvi the high internal P load coupled with a low DIN:DIP ratio resulted in a strong blue-green algal bloom in the summer of 1988. In L. Villikkalanjärvi blue-green algae were observed only in small amounts. Even in August 1990, when the DIN:DIP ratio was low enough to favor the occurrence of blue-green algae, they contributed only up to 10–15% of the total phytoplankton biomass.
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    Nutrient metabolism (C, N, P, and Si) in the trophogenic zone of a meromictic lake (1994)
    Springer
    Hydrobiologia 277 (1994), S. 17-39 
    Details
    ISSN: 1573-5117
    Keywords: carbon ; phosphorus ; nitrogen ; silica ; sedimentation ; mineralization ; meromixis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dynamics of seston and dissolved elements in a meromictic lake with high concentrations of manganese and iron in the monimolimnion were studied through an annual cycle. This publication presents results for assimilation, sedimentation and recovery of nutrients (C, N, P, and Si) in the trophogenic zone. Phosphorus deficiency kept the productivity of the diatom dominated phytoplankton at an oligotrophic level. High concentrations of iron in influent streams and redistribution followed by precipitation of iron during periods of partial turnover removed phosphorus from the water. High concentrations of manganese and sulfate did not have the anticipated fertilizing effect, and recovery of nutrients from the depth of the lake was negligible. Mass balance calculations indicate that liberation of phosphorus from the sediments in the trophogenic zone was most important for the maintenance of primary production. 75% of carbon, 80% of nitrogen and 25% of phosphorus assimilated by the phytoplankton was mineralized in the trophogenic zone. Silica was effectively regenerated from the littoral zone during the decline of diatom blooms. Nitrogen and silica retention was 45% of the external load compared to 66% for phosphorus.
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    Hydrologic control of litter decomposition in seasonally flooded prairie marshes (1994)
    Springer
    Hydrobiologia 286 (1994), S. 155-165 
    Details
    ISSN: 1573-5117
    Keywords: decomposition ; marsh ; litter ; nitrogen ; Scolochloa festucacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of seasonal inundation on the decomposition of emergent macrophyte litter (Scolochloa festucacea) was examined under experimental flooding regimes in a northern prairie marsh. Stem and leaf litter was subjected to six aboveground inundation treatments (ranging from never flooded to flooded April through October) and two belowground treatments (nonflooded and flooded April to August). Flooding increased the rate of mass loss from litter aboveground but retarded decay belowground. Aboveground, N concentration decreased and subsequently increased earlier in the longer flooded treatments, indicating that flooding decreased the time that litter remained in the leaching and immobilization phases of decay. Belowground, both flooded and nonflooded litter showed an initial rapid loss of N, but concentration and percent of original N remaining were greater in the nonflooded marsh throughout the first year. This suggested that more N was immobilized on litter under the nonflooded, more oxidizing soil conditions. Both N concentration and percent N remaining of belowground litter were greater in the flooded than the nonflooded marsh the second year, suggesting that N immobilization was enhanced after water-level drawdown. These results suggest different mechanisms by which flooding affects decomposition in different wetland environments. On the soil surface where oxygen is readily available, flooding accelerates decomposition by increasing moisture. Belowground, flooding creates anoxic conditions that slow decay. The typical hydrologic pattern in seasonally flooded prairie marshes of spring flooding followed by water-level drawdown in summer may maximize system decomposition rates by allowing rapid decomposition aboveground in standing water and by annually alleviating soil anoxia.
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    Influence of small river conditions on the abundance of Tubificidae (1994)
    Springer
    Hydrobiologia 278 (1994), S. 129-131 
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    ISSN: 1573-5117
    Keywords: small rivers ; water contamination ; Tubificidae ; bacteria ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two small rivers, the Yerik and Nezhegolyok, were studied seasonally in 1979–1980. Increase in concentration of nitrogen and phosphorus compounds in the river water as well as proliferation of enterococci and enterobacilli favoured the abundance of Tubificidae while, at the same time, their numbers were reduced by chironomids and leeches.
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    The importance of avian-contributed nitrogen (N) and phosphorus (P) to Lake Grand-Lieu, France (1994)
    Springer
    Hydrobiologia 279-280 (1994), S. 133-147 
    Details
    ISSN: 1573-5117
    Keywords: eutrophication ; birds ; lake ; nitrogen ; phosphorus ; eutrophisation ; oiseaux ; lac ; azote ; phosphore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le plus grand lac de plaine français, Grand-Lieu, est actuellement largement eutrophisé. Le but de cette étude est d'estimer l'importation annuelle de N et P par les fientes des oiseaux qui s'alimentent à l'extérieur du lac, et de la comparer avec les apports des rivières alimentant le lac. Deux années sont comparées: 1981–82 et 1990–91. Les populations nicheuses (jusqu'à 956 couples de hérons cendrés et 136 couples de grands cormorans et 30 000 canards) et hivernantes (jusqu'à 17 000 canards, 1100 grands cormorans, 15 000 goélands et 2,4 millions d'étourneaux) ont respectivement importé 5800 kg de N total en 1981–82 et 7640 en 1990–91, soit 0,7% et 0,4% des entrées totales du système, et 2000 à 2530 kg de P total soit 2,4 et 6,6% des entrées. Les étourneaux sont responsables des trois quarts des apports d'azote par les oiseaux, et les canards de l'essentiel du reste, tandis que la part des étourneaux baisse pour le phosphore (36% en 1981–82 et 41% en 1990–91), au profit des Canards et des Hérons (respectivement 35% et 27% en 1981–82, 22% et 24% en 1990–91). Mais pendant la phase de croissance végétale (avril–septembre), la part des oiseaux monte jusqu'à 37% des entrées totales de phosphore. L'action localisée des colonies d'oiseaux piscivores est significative, avec une teneur de phosphore 42 fois plus grande dans l'eau sous la colonie qu'à l'extérieur des colonies. A l'échelle du l'ac, l'action actuelle globalement mineure des oiseaux sur les apports totaux d'azote et de phosphore est largement due à l'augmentation catastrophique des apports d'origine humaine (agriculture intensive et stations d'épuration). La teneur moyenne des rivières atteint désormais 10 mg l−1 de N (jusqu'à 23 mg en crue) et 394 mg m−3 de P (jusqu'à 468 mg en crue). Avant cette pollution généralisée, l'eau des rivières bretonnes ne contenait dans les années 1960 que 0,1 à 1,1 mg l−1 de N et 1 à 5 mg m−3 de P lors des périodes de débits maximum. A cette époque, les oiseaux représentaient probablement jusqu'à 36% des apports de N et 95% des apports de P dans les entrées du système lacustre.
    Notes: Abstract The largest natural lake in France, Grand-Lieu, has suffered eutrophication. The objective of the study was to estimate the annual input of nutrients (N, P) resulting from avian excrement, deposited by birds feeding out of the lake and returning to its waters for breeding or roosting, as compared to the input by the rivers that enter in the lake. Two years are compared: 1981–82 and 1990–91. About 1600–2000 breeding herons and cormorants, 20 000–33 000 wintering ducks, gulls and cormorants and 1–2.4 million starlings deposited about 5800 kg total N in 1981–82 and 7640 kg in 1990–91. Respectively, 2000 and 2530 kg total P were deposited over the same time periods. These represent 0.7% and 0.4% of the total N input of the lake and 2.4 and 6.6% of the total P input in 1981–82 and 1990–91. Starlings account for 74% of the N and mallards most of the rest. P input by starlings (36% in 1981–82, 41% in 1990–91), and by mallards and herons (35% and 27% in 1981–82 and 22% and 24% in 1990–91 respectively) plays an appreciable role among birds. During the plant growing period (April–September), the contribution by birds can increase to 37% of total P input of the lake. Piscivorous bird colonies concentrate Phosphorus 42 times more within the colony than outside the colony. Overall, the role birds play in total N and P input is relatively small due to very high inputs from human sewage and agriculture run off. The monthly mean concentration of the water of the two rivers reaches currently 10 mg l−1 of N (to 23 mg during peak floods) and 394 mg m−3 of P (to 468 mg during peak floods). Earlier, for example in the 1960's, water in Brittany only contained 0.1 to 1.1 mg 1−1 of N and 1 to 5 mg m−3 of P during the maximum flow period. At this time, birds could probably have represented annually up to 37% of the N input and up to 95% of the P input to the lake.
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    Using hydrophilic polymers to control nutrient release (1994)
    Springer
    Nutrient cycling in agroecosystems 38 (1994), S. 53-59 
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    ISSN: 1573-0867
    Keywords: controlled-release fertilizer ; gel ; iron ; manganese ; nitrogen ; polyacrylamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Using diverse technological approaches, many types of delivery devices have been used to supply plant nutrients at a controlled rate in the soil. One new approach is the use of hydrophilic polymers as carriers of plant nutrients. These polymers may be generally classified as 1) natural polymers derived from polysaccharides, 2) semi-synthetic polymers (primarily cellulose derivatives), and 3) synthetic polymers. By controlling the reaction conditions when forming the polymers, various degrees of cross-linking, anionic charge, and cationic charge can be added, thereby changing their effectiveness as fertilizer carriers. When fertilizer-containing solutions are mixed with hydrophilic polymers to form a “gel” prior to application in the soil, the release of soluble nutrients can be substantially delayed compared with soluble fertilizer alone. The effectiveness of a specific controlled-release polymeric system is determined in part by its specific chemical and physical properties, its biodegradation rate, and the fertilizer source used. Addition of some polymers with nutrients has been shown to reduce N and K leaching from well-drained soils and to increase the plant recovery of added N, P, Fe, and Mn in some circumstances
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    Application of15N-labelled urea to sugar cane through a drip-irrigation system in Mauritius (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 223-228 
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    ISSN: 1573-0867
    Keywords: drip-fertigation ; efficiency ; nitrogen ; sugar cane ; uptake ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen (N) fertilizer use efficiency by sugar cane in Mauritius rarely exceeds 40%. Since drip-irrigation delivers water uniformly and directly to the root zone with little run-off, application of N via the drip-irrigation system could therefore provide a means of enhancing fertilizer N use by sugar cane. A study was initiated in Mauritius to determine what benefits would accrue from applying urea (120 kg N per ha) to sugar cane through the drip-irrigation network. The data obtained showed that the efficiency of fertilizer N when measured at harvest was nearly doubled by supplying the N daily over 10 to 20 weeks by fertigation. Increased yields of sugar or cane did not, however, accompany the improved N use efficiency. Furthermore, when N was applied through the drip-irrigation network, recovery of N at harvest did not accurately reflect N use efficiency.
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    Urea management for lowland transplanted rice as affected by application of farmyard manure (1994)
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    Nutrient cycling in agroecosystems 39 (1994), S. 199-203 
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    ISSN: 1573-0867
    Keywords: farmyard manure ; floodwater ; nitrogen ; Oryza sativa L. ; partial pressure of ammonia ; urea ; Vietnam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Farmyard manure (FYM) applied to rice-growing soils can substitute for industrial fertilizers, but little is known about the influence of FYM on the effectiveness and optimal management for industrial N fertilizers. A field experiment was conducted in northern Vietnam on a degraded soil in the spring season (February to June) and summer season (July to November) to determine the effect of FYM on optimal timing for the first application of urea. The experimental design was a randomized complete block with two rates of basal incorporated FYM (0 or 6 Mg ha−1) in factorial combination with two timings of the first application of 30 kg urea-N ha−1 (basal incorporated before transplanting or delayed until 14 to 16 d after transplanting). The FYM was formed by composting pig manure with rice straw for 3 months. Basal incorporation of FYM, containing 23 kg N ha−1, increased rice grain yield in both seasons. The yield increase cannot be attributed to reduced ammonia loss of applied urea-N, because FYM did not reduce partial pressure of ammonia (pNH3) following urea application in either season. Basal and delayed applications of urea were equally effective in the absence of FYM, but when FYM was applied rice yields in both seasons were higher for delayed (mean = 3.2 Mg ha−1) than basal (mean = 2.9 Mg ha−1) application of urea. Results suggest that recommendations for urea timing in irrigated lowland rice should consider whether farmers apply FYM.
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    Response of ensete (Ensete ventricosum W.) to mineral fertilizers in southwest Ethiopia (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 107-113 
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    ISSN: 1573-0867
    Keywords: Ensete ventricosum ; fertilizer response ; nitrogen ; phosphorus ; potassium ; sulphur ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ensete (Ensete ventricosum W. Cheesm.) is a root crop which stores starch in the root and in the lower part of the stem. It is grown in the southwest of Ethiopia and due to its drought resistance, it is of outstanding importance for the supply of food to the local population. Until now virtually nothing is known about the response of Ensete to fertilizer application. Field trials carried out on three representative soils in Ethiopia showed that Ensete biomass yields were increased significantly on all three soils by nitrogen and phosphorus application. Potassium had only marginal effect on biomass growth but favourably influenced starch production. Sulfate application had no major impact on growth and starch yield. The yield response was well related to the level of available nutrients in the soil, as determined by electroultrafiltration (EUF). Leaf analysis provided preliminary evidence that optimum levels of N, P, and K may be 3.8%, 0.3%, and 4.8%, respectively.
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    Transport coefficients of argon, nitrogen, oxygen, argon-nitrogen, and argon-oxygen plasmas (1994)
    Springer
    Plasma chemistry and plasma processing 14 (1994), S. 451-490 
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    ISSN: 1572-8986
    Keywords: Transport coefficients ; transport properties ; viscosity ; thermal conductivity ; electrical conductivity ; diffusion coefficient ; Chapman Enskog method ; argon ; nitrogen ; oxygen ; plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Calculated values of the viscosity, thermal conductivity, and electrical conductivity of argon, nitrogen, and oxygen plasmas, and mixtures of argon anti nitrogen and of argon anti oxygen, are presented. In addition, combined ordinary, pressure, and thermal diffusion coefficients are given for the gas mixtures. These three combined diffusion coefficients fully describe di fusion of the two gases, irrespective of their degree of dissociation or ionizati on. The calculations, which assume local thermodynamic equilibrium, are performed! for atmospheric-pressure plasmas in the temperature range /torn 300 to 30,000 K. A number of the collision integrals used in calculating the transport coefficients are significantly more accurate than values used in previous theoretical studies, resulting in more reliable values of the transport coefficients. The results are compared with those of published theoretical and experimental studies.
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    Assimilation of ethylenediamine as nitrogen source by the cyanobiont Nostoc ANTH (1994)
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 477-478 
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    ISSN: 1573-0972
    Keywords: Ethylenediamine ; glutamine synthetase ; nitrogen ; Nostoc ANTH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Nostoc ANTH metabolizes ethylenediamine (EDA) as sole nitrogen source but not as a carbon source. EDA is assimilated by the glutamine synthetase-glutamate synthase pathway. EDA represses heterocyst formation and nitrogenase activity but this is reversed by l-methionine-dl-sulphoximine.
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    Nitrogen effects on rhizosphere processes of range grasses from different successional seres (1994)
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    Plant and soil 161 (1994), S. 241-250 
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    ISSN: 1573-5036
    Keywords: carbon ; microorganisms ; nitrogen ; plant succession ; range grasses ; rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen and rhizosphere microorganism effects on nitrogen and carbon dynamics of Sitanion hystrix (early successional species), Stipa comata and Poa secundu which are (mid-successional species), and Agropyron spicatum (late successional species) were evaluated in a growth chamber study. Rhizosphere inocula resulted in increased nitrogen in both root and shoot tissue, and also of water-extractable carbon in the rhizosphere. Plant species, rhizosphere inocula and nitrogen level showed a three-way significant interaction for total and plant-available nitrogen. Rhizosphere microbe presence resulted in higher plant-available nitrogen in the rhizosphere of S. hystrix and less with A. spicatum, suggesting nitrogen immobilization with the later successional grass. Higher nitrogen resulted in decreased active bacteria in the rhizosphere of all plants tested, and decreased fungal hyphal lengths in the rhizosphere of the later successional P. secunda and A. spicutum. Exudate carbon in the rhizosphere of the late successional species A. spicatum, was more recalcitrant, which also may contribute to nitrogen immobilization. These differential responses of early- and late-successional grasses may be important factors contributing to plant succession.
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    Comparison between a chemical and a biological method to determine the N mineralization potential of temperate-humid region soils (1994)
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    Plant and soil 162 (1994), S. 147-150 
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    ISSN: 1573-5036
    Keywords: biological method ; chemical method ; mineralization potential ; nitrogen ; soil incubation ; temperate humid-zone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potentially mineralizable organic N of 33 different soils was estimated by a chemical test (hot extraction with 2N KCl) and the values compared with those previously obtained by a biological method (aerobic incubation in the laboratory). On average, the organic N solubilized by the chemical procedure was significantly lower than that mineralized by a two weeks aerobic incubation for all the soils as a whole. The same was true for soils developed over acid rocks and over sediments. However, the values obtained for the soils developed over limestone and basic rocks were similar by both methods. The values obtained by both methods were not significantly correlated neither when considering all soils together nor when considering different groups according to soil management or parent material. Significant correlations between both methods were only found when the soils were separated into two groups according to their organic N content: soils with less than 400 mg N 100 g−1 soil and soils with more than 400 mg N 100 g−1 soil. The organic N solubilized by the chemical procedure was significantly correlated with the hexosamine-N content; however, it was not correlated with the factors that control the biological mineralization of the organic N, except with the soluble Al content. Therefore, the chemical extraction did not seem to address the biologically active N pool in a selective way.
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    A coded checklist and ecological indicator values of freshwater diatoms from The Netherlands (1994)
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    Aquatic ecology 28 (1994), S. 117-133 
    Details
    ISSN: 1573-5125
    Keywords: checklist ; diatoms ; The Netherlands ; pH ; salinity ; nitrogen ; oxygen ; saprobity ; trophic state ; moisture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This first comprehensive checklist of the diatoms from fresh and weakly brackish water in The Netherlands comprises 948 taxa, belonging to 776 species in 56 genera. The generaNavicula, which has a very wide ecological amplitude, andNitzschia, which has many pollution tolerant species, are most numerous. Each taxon is identified with a unique eight-letter code, to facilitate computer processing of data. Ecological indicator values for pH, salinity, nitrogen uptake metabolism, oxygen, saprobity, trophic state and moisture are presented.
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    Terpenes and phenolics in response to nitrogen fertilization: A test of the carbon/nutrient balance hypothesis (1993)
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    Chemoecology 4 (1993), S. 3-7 
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    ISSN: 1423-0445
    Keywords: carbon/nutrient balance hypothesis ; carbon allocation ; fertilization ; phenolics ; nitrogen ; terpene ; Abies grandis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogen fertilization resulted in a linear increase in the growth ofAbies grandis seedlings, but linear decrease in foliage concentrations of phenolic compounds. These data are consistent with the inverse relationship between growth and production of carbonbased secondary chemicals predicted by the carbon/nutrient balance (CNB) hypothesis. However, in contrast to predictions of the CNB hypothesis, nitrogen fertilization had no effect on foliage terpene concentrations. The results suggest that not all carbon-based chemicals respond in the same manner to environmental variation, and that the carbon/nutrient balance hypothesis does not adequately explain all patterns of environmentally-induced variation in secondary metabolism.
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    What controls levels of dissolved phosphate and ammonium in surface waters? (1993)
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    Aquatic sciences 55 (1993), S. 132-142 
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    ISSN: 1420-9055
    Keywords: nitrogen ; phosphorus ; uptake ; regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dissolved inorganic nutrient pools are small relative to particulate pools, and dissolved pools turnover rapidly. It has been observed that pools change little from day to day on the sampling scales usually employed. A simple model is presented where uptake and regeneration rates balance to cause a local steady state concentration for dissolved inorganic nutrients. Enrichment and dilution perturbation experiments with lake water support the idea of steady state nutrient concentrations. Although inorganic nutrient concentrations are often controlled by biota, the absolute concentrations present tell little about the activity of that biota.
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    Simulated effects of precipitation and nitrogen on Serengeti grassland productivity (1993)
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    Biogeochemistry 22 (1993), S. 157-178 
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    ISSN: 1573-515X
    Keywords: Serengeti ; productivity ; precipitation ; nitrogen ; grazing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract In the Serengeti National Park, Tanzania, precipitation and soil nitrogen vary greatly between northwestern tallgrass areas and southeastern shortgrass areas, with the tallgrass having higher total precipitation and lower soil fertility. We used a model of grassland productivity, carbon/nitrogen cycling, and abiotic factors to test the hypothesis that tallgrass productivity is limited primarily by nitrogen availability while shortgrass productivity is limited by water. Under observed grazing intensities and ungrazed conditions, precipitation exerted primary control over grassland productivity for both regions, with differences in soil texture mediating soil water availability to the grasses. Mineral nitrogen availability interacted with water availability to influence productivity at precipitation levels ⩾ 130% of the mean. Nitrogen mineralization and precipitation were positively related for each grassland type, however, nitrification varied both between grassland types and between grazed and ungrazed conditions. Combined mineralization and nitrification could not maintain soil mineral nitrogen levels in the face of plant nitrogen uptake stimulated by increased precipitation, thus providing the mechanism by which nitrogen becomes a secondary limiting factor for both grasslands. Model experiments indicated that the pattern of primary limitation by precipitation and secondary limitation by nitrogen was robust to model assumptions concerning ungulate deposition of urine and dung nitrogen to the soil.
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    Mass loss and nitrogen dynamics in decomposing acid forest litter in the Netherlands at increased nitrogen deposition (1993)
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    Biogeochemistry 20 (1993), S. 45-62 
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    ISSN: 1573-515X
    Keywords: atmospheric deposition ; forest ecosystems ; litter decomposition ; The Netherlands ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Litterbag experiments were carried out in five forest ecosystems in the Netherlands to study weight loss and nitrogen dynamics during the first two years of decomposition of leaf and needle litter. All forests were characterized by a relatively high atmospheric nitrogen input by throughfall, ranging from 22–55 kg N ha−1 yr−1. Correlation analysis of all seven leaf and needle litters revealed no significant relation between the measured litter quality indices (nitrogen and lignin concentration, lignin-to-nitrogen ratio) and the decomposition rate. A significant linear relation was found between initial lignin-to-nitrogen ratio and critical nitrogen concentration, suggesting an effect of litter quality on nitrogen dynamics. Comparison of the decomposition of oak leaves in a nitrogen-limited and a nitrogen-saturated forest suggested an increased nitrogen availability. The differences in capacities to retain atmospheric nitrogen inputs between these two sites could be explained by differences in net nitrogen immobilization in first year decomposing oak leaves: in the nitrogen-limited oak forest a major part (55%) of the nitrogen input by throughfall was immobilized in the first year oak leaf litter. The three coniferous forests consisted of two monocultures of Douglas fir and a mixed stand of Douglas fir and Scots pine. Despite comparable litter quality in the Douglas fir needles in all sites, completely different nitrogen dynamics were found.
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    Productivity and adaptive capacity of winter wheat landraces and modern cultivars grown under low-fertility conditions (1993)
    Springer
    Euphytica 70 (1993), S. 27-33 
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    ISSN: 1573-5060
    Keywords: Wheat ; Triticum aestivum ; landrace ; semidwarf ; phosphorus ; nitrogen ; fertilization ; genetic improvement ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In recent decades, most winter wheat (Triticum aestivum L.) breeding in the United States has been done in field nurseries in which the soil receives ample fertilization. To determine the effects of these breeding efforts on productivity under low-fertility conditions, we evaluated twenty-nine winter wheat genotypes (seven Asian landraces; thirteen standard-height U.S. cultivars released between 1874 and 1971; and nine semidwarf cultivars released between 1977 and 1988) under severe fertility stress at three Kansas, USA locations. Experiments included fertilized and unfertilized treatments. The modern, semidwarf cultivars yielded 18% and 20% more, on average, than landraces and standard-height cultivars under low and high fertility, respectively; however, only the latter difference reached the 5% significance level. At only one location (Hays) was there a significant genotype X fertility interaction: there, 89% of the semidwarf cultivars, only 8% of the standard cultivars, and 57% of the landraces responded to fertilization. The regression coefficient of mean grain yield (unfertilized) on year of introduction or release for standard and semidwarf cultivars was zero, indicating that a century of breeding has produced no genetic improvement in performance under these low-fertility conditions. Although we found that the usual yield advantage of modern cultivars is not expressed under very low fertility, we saw no evidence that older cultivars are superior under those conditions.
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    Influence of nitrogen and phosphorus fertilizers on amount and nutrient content of litterfall in a regrowth eucalypt forest (1993)
    Springer
    New forests 7 (1993), S. 33-47 
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    ISSN: 1573-5095
    Keywords: eucalypt ; regrowth forest ; litter ; litterfall ; fertilizer ; nitrogen ; nutrient cycling ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of fertilizer treatment on nutrient transfers to the forest floor were examined in regrowth Eucalyptus diversicolor F. Muell. forest. Dry weight and nutrient content of leaf litterfall and total litterfall were measured for 3 years in a stand to which two levels of N (0, 200 kg ha-1 year-1) were applied each year at each of three levels of a single initial application of P (0, 30, 200 kg ha-1). Annual accessions of litter to the forest floor were significantly increased by additions of both N (by 17%, 18% and 21% in the 3 years) and 200 kg P ha-1 (by 8%, 8% and 4% in the 3 years) but there was no interaction between effects of N and P treatments. Fertilizer application also had a significant effect on the nutrient content of leaf litterfall and total litterfall. Concentration of N in leaf litterfall was 9% to 23% greater on plots treated with N fertilizer compared to untreated plots. The amounts of N in litterfall were about 30% greater on N-treated compared to untreated plots. On plots treated with 200 kg P ha-1, P concentrations in leaf litter were 50% to 100% greater than in litter from plots receiving no P. Application of 200 kg P ha-1 increased the amounts of P in annual litterfall by 32% to 87%. The greatest increase in P accessions occurred soon after fertilizer treatment. The amounts of Ca, K, and Na in litterfall were also significantly increased by fertilizer application. For Ca and K this was due partly to increases in element concentrations in litterfall following application of treatments. The effect of fertilizers on internal recycling of plant nutrients and on litter accumulation and nutrient dynamics in forest floor litter is discussed.
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    Nutrient limitations to plant growth during primary succession in Hawaii Volcanoes National Park (1993)
    Springer
    Biogeochemistry 23 (1993), S. 197-215 
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    ISSN: 1573-515X
    Keywords: chronosequence ; montane tropical forest ; nitrogen ; soil development ; phosphorus ; tropical forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We determined the effects of nutrient amendments on plant growth in three tropical montane rainforest sites representing a sequence of soil ages (〈 30, 200, and ≈ 2000 y). Factorial fertilization with nitrogen, phosphorus, and all other essential nutrients (combined) was applied to the two younger sites; only nitrogen was applied to the oldest one. Nitrogen supply represented the most important limitation to plant growth in the two younger sites; additions of nitrogen caused significant increases in tree diameter increment, height growth, litterfall, and most other growth-related parameters. In contrast, nitrogen additions had no significant effect on plant growth in the oldest site. Phosphorus additions increased extractable soil phosphorus and plant tissue phosphorus, but did not increase plant growth at the young sites. The results are consistent with Walker & Syers' (1976) model for the control of nutrient limitation during soil development.
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    The potential of alley cropping in improvement of cultivation systems in the high rainfall areas of Zambia. III. Effects on soil chemical and physical properties (1993)
    Springer
    Agroforestry systems 21 (1993), S. 117-132 
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    ISSN: 1572-9680
    Keywords: alley cropping ; maize ; nitrogen ; organic matter ; soil fertility ; Leucaena leucocephala ; Flemingia congesta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A detailed study of the soil chemical and physical properties in seven-year-old alley cropping trial containingLeucaena leucocephala andFlemingia congesta in Northern Zambia is described. There was a strong correlation between the maize yield and the total amount of nitrogen applied, both from prunings and fertiliser, suggesting that a major reason for the observed benefit from alley cropping, particularly withLeucaena, was due to an improvement in nitrogen supply.Leucaena produced significantly more biomass, and its leaves had higher concentrations of nitrogen, phosphorous and potassium and lower C/N and C/P ratios than did those ofFlemingia. There was also evidence that the trees had a beneficial effect on other soil chemical properties; under the hedgerows, particularly those ofLeucaena, there were higher levels of organic carbon, Mg, K and ECEC, and pH values were also highest. It is suggested that higher levels of organic carbon in the alley crop treatments were responsible for the improvements observed in soil physical properties. Lower bulk density, lower penetration resistance, and a higher infiltration rate and pore volume fraction were measured in the alley crops, although there was no significant change in the soil water release parameters. A deteriorating effect of constant applications of nitrogen fertiliser on soil fertility was observed; as the level of urea application increased, there were significant decreases in Mg, K and pH, increases in Al and soil acidity, and higher penetrometer resistance. These results highlight the urgent need for further research on biological methods of maintaining soil fertility.
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    Nitrogen mass balances and denitrification rates in central Ontario Lakes (1993)
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    Biodegradation 20 (1993), S. 195-212 
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    ISSN: 1572-9729
    Keywords: denitrification ; lake ; mass balance ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen mass balances for seven unproductive lakes and 20 forested catchments in central Ontario were measured between 1977 and 1989. Average annual lake denitrification rates calculated with the N/P ratio method were strongly correlated with summer anoxic factor (extent of surficial sediment anoxia) whereas denitrification rates calculated with a210Pb sediment N accumulation method were poorly correlated with the anoxic factor suggesting that the N/P method is superior. Substantial denitrification occurred in all lakes — an average of 36% of TN inputs or 75% of the net gain. On a regional area-weighted basis, 67% of bulk atmospheric TN deposition was stored or denitrified terrestrially, 12% was denitrified in lakes, 4% was stored in lake sediments, and 17% was exported from lakes. N/P ratios were generally less in streams than in precipitation suggesting preferential N retention in catchments, whereas the N/P ratios in lake outputs were slightly higher than lake input ratios, suggesting preferential P retention in lakes. This is consistent with the notion that P-limited lakes can exist adjacent to N-limited forests.
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    The effect of cattle foot traffic on soil compaction in a silvo-pastoral system (1993)
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    Agroforestry systems 21 (1993), S. 1-10 
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    ISSN: 1572-9680
    Keywords: silvo-pasture ; compaction ; cattle traffic ; penetrometer ; bulk density ; nitrogen ; seedlings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper reports on the extent of soil compaction due to cattle traffic around hardwood and softwood tree seedlings established in existing pasture, and subject to cattle pressure. A higher soil penetrometer resistance in the grazed areas pointed to a significant change in soil structure (i.e. dry bulk density) as a result of cattle traffic in the area. In a related experiment comparing the effect of three different levels of soil compaction on tree seedling growth and nitrogen cycling it was found that water infiltration and nitrogen uptake were reduced in soils treated with a medium and high level of compactive effort. This resulted in a slower rate of growth of the tree seedlings. The addition of an additional nitrogen source improved seedling growth in both the medium and high density compactive treatments.
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    How do non-differentiating bacteria adapt to starvation? (1993)
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    Antonie van Leeuwenhoek 63 (1993), S. 333-341 
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    ISSN: 1572-9699
    Keywords: survival ; starvation ; stress ; Vibrio ; carbon ; nitrogen ; phosphorus ; protein synthesis ; carbon starvation stimulon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Non-differentiating bacteria adapt to starvation induced growth arrest by a complex turn-on/turn-off pattern of protein synthesis. This response shows distinct similarities with those of spore formation in differentiating organisms. A substantial amount of information on the non-growth biology of non-differentiating bacteria can be derived from studies onVibrio strains. One important result is that carbon rather than nitrogen or phosphorus starvation leads to the development of a starvation and stress resistant cell in these organisms. Hence, we have attempted to characterize the carbon starvation stimulon. By the use of two-dimensional gel electrophoresis of pulse-labelled cells and transposon mutagenesis, using reporter gene constructs, the identity and function of some members of the carbon starvation stimulon have been elucidated. Moreover, regulatory genes of the starvation response have been identified with these techniques. Current studies primarily address the identity and function of these genes. The role of transcript modification and stability for both long term persistence during starvation as well as the efficient recovery of cells which occurs upon nutrient addition is also addressed. It is suggested that an understanding of the functionality of the translational machinery is essential for the understanding of these adaptive pathways. This contribution also discusses the diversity of the differentiation-like response to starvation in different bacteria and whether a general starvation induced programme exists.
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    Special Equations of State for Methane, Argon, and Nitrogen for the Temperature Range from 270 to 350 K at Pressures up to 30 MPa (1993)
    Springer
    International journal of thermophysics 14 (1993), S. 699-725 
    Details
    ISSN: 1572-9567
    Keywords: argon ; caloric properties ; density ; equation of state ; Helmholtz function ; methane ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In order to describe the thermodynamic behavior of methane, argon, and nitrogen in the so-called “natural-gas region,” namely, from 270 to 350 K at pressures up to 30 MPa as accurate as possible with equations of a very simple form, new equations of state for these three substances have been developed. These equations are in the form of a fundamental equation in the dimensionless Helmholtz energy; for calculating the pressure or the density, the corresponding equations explicit in pressure are also given. The residual parts of the Helmholtz function representing the behavior of the real gas contain 12 fitted coefficients for methane, 8 for argon, and 7 for nitrogen. The thermodynamic relations between the Helmholtz energy and the most important thermodynamic properties and the needed derivatives of the equations are explicitly given; to assist the user there is also a table with values for computer-program verification. The uncertainties when calculating the density ρ, the speed of sound w, the isobaric specific heat capacity c p, and the isochoric specific heat capacity c v are estimated as follows. For all three substances it is Δρ/ρ≤±0.02 % for p≤ 12 MPa and Δρ/ρ ≤ ±0.05% for higher pressures. For methane it is Δw/w≤±0.02% for p≤10 MPa and Δw/w≤+-0.1% for higher pressures; for argon it is Δw/w≲-0.1 % for p≤ 7 MPa, Δw/w≤±0.3 % for 7 〈p≤30 MPa; and for nitrogen it is Δw/w≤±0.1% for p≤1.5 MPa and Δw/w±0.5% for higher pressures. For all three substances it is Δc p/c p≤±1 % and ΔC v/C v≤±1 % in the entire range.
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    Frost formation in the ecotonal zone and its role for release of nutrients (1993)
    Springer
    Hydrobiologia 251 (1993), S. 65-72 
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    ISSN: 1573-5117
    Keywords: Frozen littoral ; frost heave ; nutrient release ; nitrogen ; phosphorus ; calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In winter, the littoral substrate of ecotonal zones along north Swedish rivers and lakes freezes. Even if the littoral is flooded at freeze-up, the ice freezes solid to the shore substrate due to low temperature combined with a gradual decrease in water level during winter. Frost conditions were studied during an 8-year period along eight littoral transects in the River Vindelälven and adjacent riverside lagoons. Heavy frost heave with formation of needle ice was observed in several places. Nutrient release was suggested to take place due to the frost process. Sediment was taken to a laboratory experiment where samples with sediment and water were kept under unfrozen and frozen conditions during six months. N (total-N) and Ca were significantly released to the water, while P (total-P) did not show any clear movement from the frozen sediment. The results indicate that frost processes in ecotonal zones are involved in the movement of nutrients between sediment and water.
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    Transport and retention of matter in riparian ecotones (1993)
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    Hydrobiologia 251 (1993), S. 95-101 
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    ISSN: 1573-5117
    Keywords: Land/stream ecotones ; bank runoff ; aerial drift ; retention ; carbon ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ‘stream’ ecosystem is described as a three-layered system, vertically as well as horizontally. The land/stream ecotone is defined as the area where lotic and edaphic characters overlap at the time of observation. The study site — ‘Oberer Seebach’, near the Biological Station Lunz — and the methods employed are described. Only a surprisingly small fraction (less than 10 %) of total imports is transported across the surface ecotones. The driving variables determining bank runoff and aerial drift are described and discussed. The importance of channel areas which are periodically flooded is stressed.
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    Retention of nitrogen and phosphorus in a Danish lowland river system: implications for the export from the watershed (1993)
    Springer
    Hydrobiologia 251 (1993), S. 123-135 
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    ISSN: 1573-5117
    Keywords: retention ; core-sampling ; phosphorus ; nitrogen ; resuspension ; export
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a Danish lowland river system intensive measurements were made, in four 80 m reaches, of the nitrogen (N) and phosphorus (P) stored in the stream sediment. The results were used for calculation of the total retention in the river system during two summers (June to August). In addition, the mobilization of nutrients from the stream bottom in autumn 1987 was compared with the export from the watershed. During the study period (June 1987 to September 1988) the amounts of N and P stored in stream reaches were determined fortnightly using a core-sample technique. In reaches dominated by submersed macrophytes, 25–40 g N m−2 and 20–30 g P m−2 were stored during two summers, against only 10–15g N and P m−2 for sandy and gravely reaches. In riparian zones with emergent macrophytes the retention was even higher than in the submersed macrophytes. Gross retention exceeded net retention by a factor of two to three. Net retention of P in the river system during the summer of 1987 was equal to the summer export from the watershed. On an annual basis, retention in the summer constituted 20% of the P export. In contrast, retention in the summer of 1988 amounted to 60% of the total P export during the same period (38% reduction) and 22% in comparison with the annual export. The corresponding figures for N were lower, showing reductions of 16% and 12% of the export of total N in the two summer periods, and about 1% of the annual exports. In September 1987 6.4% of the total N export and 65% of the total P export from the watershed consisted of resuspended material. In 1987 the N and P retained during the summer was almost completely resuspended during storm events during September to November.
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    Storage and dynamics of organic matter in different springs of small floodplain streams (1993)
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    Hydrobiologia 251 (1993), S. 199-209 
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    ISSN: 1573-5117
    Keywords: spring ; karst ; interstitial aquifer ; nitrogen ; carbon ; organic matter retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The flow of groundwater through the sediment layer (underflow or hyporheic zone) of streams and at the origin of streams can influence organic matter uptake dynamics of floodplain. The River Rhône floodplain has limestone foothills. Here we studied 2 karstic and 2 interstitial springs differing by aquifer geology. Organic matter, physico-chemical conditions were compared between these springs during two seasons (from March to September 1989) and at different depths (0, −20 cm, −40 cm). Temperatures indicated large differences in underflow between springs, in their relation to the surrounding environment, and between seasons. Springs are well oxygenated, with differences between layers. Cultivated fields supply interstitial springs with nitrates, and pools are nutrient traps. DOC was heterogeneous in space and time and correlates with VFPOC. Particulate nutrients were correlated with available surface area of sediment grains. Physical conditions of each spring were prominent in determining storage and turnover of organic matter. Each spring, by its own characteristics and dynamics regulating stability and turnover, had an effect or control on storage, transport and retention of organic matter (quality, quantity). These springs offer an example of the heterogeneity, and give a view of the diversity of patches within a floodplain. The data suggest that groundwater flow of springs may be a major factor in the functioning of floodplain tributaries.
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    Importance of flood zones for nitrogen and phosphorus dynamics in the Danube Delta (1993)
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    Hydrobiologia 251 (1993), S. 143-148 
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    ISSN: 1573-5117
    Keywords: Danube Delta ; flood zones ; phosphorus ; nitrogen ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The change of concentration of total reactive phosphorus (TRP) and dissolved inorganic nitrogen (DIN) was studied in the lower Danube river and in selected lakes situated in the wetland area of the Danube Delta. The differences Danube Delta in nutrient concentration in the river waters entering the delta and the delta in different sites (especially lakes) of the wetland area are considered to reflect retention in the system. The highest retention was found in periods of moderate and low water level when the surface-to-volume ratio of the lakes was high. In these periods the in-lake concentration of TRP and DIN could be as low as 11 and 23% of the values found in the inflowing river.
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    Nitrogen and phosphor compounds in bottom sediments: mechanisms of accumulation, transformation and release (1993)
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    Hydrobiologia 252 (1993), S. 1-22 
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    ISSN: 1573-5117
    Keywords: lakes ; reservoirs ; carbon ; nitrogen ; phosphate ; sediments ; accumulation ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper is an overview of Russian literature dealing with the accumulation, the transformations and the release of phosphate and nitrogen compounds in a great number of Russian lakes and reservoirs. A considerable data bank has been analysed. Special attention is given to the relations of N- and P-accumulation with the input and transformation of organic carbon, as well as to the release mechanisms, often in relation to eutrophication of the lakes and reservoirs. It is shown that the major input of organic matter into the sediments comes from autochthonous material, and is usually 〉 70 %. The relative importance of phytoplankton and macrophytes as sources of organic matter is discussed; it appears that trophic state, depth and other factors may have a large influence on this ratio. In shallow eutrophic lakes macrophytes may be the source of organic matter, which source can amount to 1.5–2.5 times that of phytoplankton. It is also shown that the C/N ratio is not a good indicator of the source of the organic matter, because their C/N ratios often are not very different. The decomposition rate of organic matter was analysed; it depends on trophic state and other factors. Sediment N accumulation is mostly (〉 90%) in organic form, and depends on nitrogen and organic matter inputs coming from phytoplankton or macrophytes. A correlation coefficient of 0.9–0.95 was found in 176 lakes. In 113 lakes the N accumulation was 0.11 x C accumulation, with C/N ratios between 7.4 and 12.9. Ammonification was rather constant in different groups of lakes; values were often about 20–25 mg m−2 d−1. The presence of the different forms of nitrogen in interstitial water and in adsorbed forms is discussed. The N in interstitial water is usually in the form of NH3. Sediment P-accumulation is usually in inorganic form and is related to primary production. Three different groups of sediments could be distinguished with C/P ratios of 31–100, of 101–350 and 〉 350. In hard water lakes P sedimentation was found to be 0.3–0.5 times that in soft water lakes with comparable primary production. The relative occurrence of apatite, non-apatite and residual P in sediments was calculated. In the interstitial water the P concentration appeared to be controlled by the input and decomposition of organic matter. The concentration of phosphate dissolved in the interstitial water of the top 2 cm layer is often 10–100 times lower than that of the dissolved N. The concentrations of interstitial phosphate are from a few μgl−1 up to 15 mgl−1, but the higher concentrations occur only rarely. Different types of vertical profiles of P compounds in the sediments were shown to be related with the presence of an oxidised zone, the presence of clay etc. Autochthonous apatite and non-apatite phosphates are more mobile than the allochthonous ones and are in equilibrium with interstitial phosphate. Accumulation of autochthonous apatite in sediments is controlled by decomposition of organic matter and accumulation of carbonates.
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    Transpiration by an emergent macrophyte: source of water and implications for nutrient supply (1993)
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    Hydrobiologia 271 (1993), S. 97-108 
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    ISSN: 1573-5117
    Keywords: Myriophyllum aquaticum ; parrotfeather ; nitrogen ; phosphorus ; mass flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The contribution of sediment interstitial water and the water column to the transpiration stream of Myriophyllum aquaticum (Vellozo) Verdcourt was determined to estimate the significance of mass flow in supply of sediment nutrients for plant growth. Sediment interstitial water accounted for about 2% of the water transpired over a 37 day period. Because of the small volume of water that originated in the sediment we concluded that mass flow did not significantly enhance nutrient supply to the roots of M. aquaticum. Relative growth rate (RGR) of adventitious, water roots was greater than whole plant RGR, and RGR of sediment roots was not significantly different from zero, indicating a shift in the biomass allocation after emergence of the apical meristem into the air. Water use, measured by the transpiration coefficient, averaged 260 ml H2O mg DW-1, which is similar to C-4 terrestrial plants. M. aquaticum has leaf characteristics commonly associated with xerophytic habitats. These characteristics may be necessary if a high transpiration rate and a mechanical requirement for high cell turgor pressure, required by a reliance upon hydrostatic pressure for support of the aerial stems, are mutually exclusive because of morphological constraints on hydraulic conductivity.
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    The application of the ecotone concept in defining nutrient management requirements for the upper Potomac River basin (1993)
    Springer
    Hydrobiologia 251 (1993), S. 341-349 
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    ISSN: 1573-5117
    Keywords: nutrients ; ecotones ; Potomac River ; nitrogen ; watersheds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The utility of the ecotone concept in nutrient management studies of the Potomac River basin, a large USA watershed, is examined. The MAB hypothesis suggesting that ‘the influence of an ecotone or adjacent system is proportional to the length and scope of the interfaces’ (Naiman et al., 1989) is the major focus of this paper. The land-riverine ecotone appears to have a major influence on the total nitrogen balance and river export flux of nitrogen for the upper Potomac River basin. A method of converting conventional areal flux units into linear flux rates is suggested.
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    Seasonal nitrogen dynamics in reed beds (Phragmites australis (Cav.) Trin. ex. Steudel) in relation to productivity (1993)
    Springer
    Hydrobiologia 251 (1993), S. 1-12 
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    ISSN: 1573-5117
    Keywords: littoral ; reed-belt decline ; Phragmites australis ; nitrogen ; eutrophication ; productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Shoot biomass and nitrogen, accumulated within above-ground plant biomass in autumn, correlate with nitrogen availability indicated by nitrogen content (% DM) of several shoot parts during the height of the growth period. A higher nitrogen percentage of the shoots is correlated with a higher shoot loss and subsequent substitution by branching and tillering during and continuing toward the end of the growth period. A delayed switch from the vegetative to the generative phase reduces the translocation of reserve material to the rhizome. Increasing nitrogen load is at least one of the factors causing instability and reed-belt decline.
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    Detritus and nutrient dynamics in the shore zone of lakes: a review (1993)
    Springer
    Hydrobiologia 251 (1993), S. 49-58 
    Details
    ISSN: 1573-5117
    Keywords: lake littoral ; detritus ; macrophytes ; decomposition ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The importance of detritus varies greatly among shore zones of lakes, but in a large majority of these regions detrital pathways prevail. Aside from a great spatial and seasonal variability, macrophytes and bottom sediments appear to be dominant stores of nutrients in these habitats. Macrophytes hold a central position in nutrient cycling in the shore-littoral lake zones. They are the main source of autochthonous detritus as they prevail in the total biomass of littoral organisms, and they are only rarely available as direct food of consumers. Various processes and interactions determine the role of macrophytes in nutrients dynamics. These are: the intensity of nutrient uptake and translocation, release of nutrients by healthy plants and from decomposing plants, exchange of elements between macrophytes and their periphyton, as well as interception of seston by macrophyte stands. Particular plant species differ in their time of dying and susceptibility to decomposition. The changes in decomposing material (size structure of particles and nutrient content) mean that detritus in various stages of decomposition differs in its role in trophic dynamics of shore-littoral lake zones. Several types of shore regions as regards detritus sources and retention level are discussed.
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    URL: http://dx.doi.org/10.1007/BF00007164
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    Nitrogen and phosphorus dynamics and retention in ecotones of Lake Titicaca, Bolivia/Peru (1993)
    Springer
    Hydrobiologia 251 (1993), S. 39-47 
    Details
    ISSN: 1573-5117
    Keywords: agriculture ; algae ; lake ; littoral ; macrophytes ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We are studying present conditions and consequences of material movement from land to water in the Lake Titicaca basin, and how fluxes are affected by human activities. The principal objective of this research is to describe and explain the variability in the Andean Altiplano of (a) water, nutrient and sediment fluxes from land and (b) composition, nutrient limitation and other important features of nearshore lake communities, and compare the effects of different agricultural practices (especially traditional and modern) on these factors. We are focusing on a comparison of the impacts of two forms of agriculture in this region: ancient raised fields currently under rehabilitation, and flat pastures and fields, which are more common. Results of the first year of study indicate there is substantial variability in nitrogen and phosphorus dynamics in relation to ecotone complexity (simple vs. intermediate vs. complex). Raised field sites have the beneficial effect of reducing high available nutrient concentrations (nitrate and soluble reactive phosphorus) and sediment load (measured as turbidity) as the water passes through them enroute to the lake. Aquatic vegetation (algae and macrophytes) reflect well ambient total nitrogen and phosphorus concentrations. Experimental nutrient limitation bioassays indicate that nitrogen is the most important limiting nutrient, though there is important spatial variability within the landscape, and phosphorus as well as nitrogen can be limiting.
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    URL: http://dx.doi.org/10.1007/BF00007163
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    Drainage history and land use pattern of a Swedish river system — their importance for understanding nitrogen and phosphorus load (1993)
    Springer
    Hydrobiologia 251 (1993), S. 285-296 
    Details
    ISSN: 1573-5117
    Keywords: land drainage ; nitrogen ; phosphorus ; areal coefficients ; agricultural streams ; riparian ecotones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During the 19th and the first half of the 20th century, approximately 300 km2 of lakes and wetlands, representing 29% of the River Kavlingean catchment in Southern Sweden, were drained to make land available for agriculture. Published accounts of nutrient loads from the catchment indicated that until the mid 20th century, factories and urban point sources were the major contributors of both nitrogen and phosphorus. By the middle of the 20th century, the construction of sewage treatment plants had effectively reduced phosphorus pollution. Concurrently, the land drained in the previous century underwent a more intense cultivation, with productivity being maintained by commercial fertilizers. Subsequently, net nutrient loads from agriculture continued to increase, reaching an annual load of 2652 tons total-nitrogen and 70 tons total-phosphorus for the River Kävlingeån. Whilst high nutrient leakage from agricultural watersheds may be a problem which is only recently recognized, it had its origins in nearly a hundred years of commonly accepted agricultural policy. To assess the importance of agriculture as the major source of nutrients to the River Kävlingeån system, three tributary catchment areas, differing in terms of their land use patterns (high, medium and low intensity of agricultural use), were studied and compared with literature figures. Results indicated that agricultural nutrient loss areal coefficients were substantially higher than the literature figures, demonstrating the role of agriculture as source of nutrients to the River Kävlingeån system. The agricultural land use policies of the last fifty years were revealed to be most important with regard to this role. Of such land use policies, the cultivation of the last 10–15% of land employed for agricultural use (primarily riparian ecotones) may be of most significance. The literature indicates that intense agricultural use of this final 10–15% may account for a ca. 50% increase in nitrogen loss. This suggests that one solution to the problem of agricultural diffuse pollution may lie in the restoration and sustainable management of riparian ecotones of agricultural streams.
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    URL: http://dx.doi.org/10.1007/BF00007188
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    Environment, seed rate, and N rate influence on yield of winter barley (1993)
    Springer
    Nutrient cycling in agroecosystems 34 (1993), S. 59-65 
    Details
    ISSN: 1573-0867
    Keywords: Barley ; environment ; nitrogen ; seeding rate ; yield ; yield components
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was conducted to determine the effects of rainfall and temperature during the growing season, seed rate, and N rate on grain yield and yield components of winter barley (Hordeum vulgare L.) on a Typic Haploxeralf soil in Santa Olalla (Toledo), Spain in 1986/7, 1987/8, and 1988/9. Two experiments were conducted each year using the 6-rowed variety ‘Barbarrosa’ and the 2-rowed variety ‘Reinette’. Both experiments used seed rates of 80, 160, and 240 kg ha−1 as whole plot treatments, and N rates of 0, 40, 80, 120, and 160 kg ha−1 as subplots. Responses to N depended on both the quantity and distribution of rainfall during the growing season, and temperature during grain fill. In the high rainfall, moderate grain-fill temperature year, increasing the N rate from 0 to 160 kg ha−1 increased grain yields (by 2.3 t ha−1), straw yields and the harvest index while maintaining the kernel weight for both varieties. In the low rainfall, high grain-fill temperature year, N rate had little influence on grain yield, but increased the straw yield, which reduced the harvest index, and also decreased kernel weight. Seed rate had no influence on grain yields even though wide variation in N rates, rainfall and temperatures occurred in the three-year study. Results from this study indicated that strategies to reduce (or avoid) water/high temperature stress during grain fill are necessary to assure more uniform yield responses to N application across years. However, decisions about seed rate can be made independently for conditions similar to those in this study.
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    URL: http://dx.doi.org/10.1007/BF00749961
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    Fertilization of millet cv. Souna III in Senegal: dry matter production and nutrient uptake (1993)
    Springer
    Nutrient cycling in agroecosystems 35 (1993), S. 217-226 
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    ISSN: 1573-0867
    Keywords: calcium ; dry matter distribution ; fertilizer ; harvest index ; magnesium ; manure ; millet ; nitrogen ; nutrient uptake ; phosphorus ; potassium ; Senegal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In a fertilizer and manure experiment, millet was grown under four treatments (no fertilizer or manure, farmyard manure, chemical fertilizer, and both). Grain yield and total aboveground biomass production of the unfertilized plot were relatively high. The observed differences in total dry matter production must be attributed to differences in nutrient availability, as amount of rainfall and its distribution were favourable. Results show only small differences in distribution of dry matter among the various plant organs between the best and the non-fertilized treatments. Nutrient supply from natural sources, defined as crop content of N, P, and K at maturity without fertilizer application, amounted to 104, 16 and 103 kg ha−1, respectively, which are very high values. Total uptake of calcium and magnesium is related to that of potassium, as the combined content of these three elements is linearly related to total aboveground biomass production. Minimum removal of nitrogen and phosphorus per ton grain dry matter amounts to 29 and 4kg, respectively, and 9 kg potassium per ton total aboveground dry matter. A possible double function of phosphorus as element of structural biomass and for maintenance of electro-neutrality is discussed.
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    URL: http://dx.doi.org/10.1007/BF00750640
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    Effects of nitrogen and Douglas-fir allelochemicals on development of the gypsy moth,Lymantria dispar (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 1245-1263 
    Details
    ISSN: 1573-1561
    Keywords: Artificial diet ; herbivory ; nitrogen ; Lymantria dispar ; Lepidoptera ; Lymantriidae ; monoterpenes ; nutritional ecology ; phenolics ; Pseudotsuga menziesii
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Two experiments were conducted to examine the influence of foliar nitrogen, terpenes, and phenolics of Douglas-fir on the development of gypsy moth larvae. In the first experiment, foliar concentrations of nitrogen and allelochemicals were manipulated by fertilizing 3-year-old potted seedlings with 0 or 200 ppm nitrogen. Concentrations of foliar nitrogen (0.33–2.38%) were negatively correlated with the phenolics (15.8–24.4 mg/g). Sixth-instar larvae previously reared on current-year Douglas-fir needles were allowed to feed on these seedlings. Pupal weights (312.8–995.6 mg) were positively correlated with levels of foliar nitrogen, negatively correlated with amounts of foliar phenolics, and uncorrelated with terpene concentrations. In the second experiment, terpene and phenolic extracts from Douglas-fir foliage were incorporated at natural levels into artificial diets with high and low levels of protein nitrogen. Neonate larvae grew faster and were larger on the high nitrogen control diet (4.1–4.5%), however, fourth instars performed better on the control diet with low nitrogen levels (2.5–2.7%). Foliar terpenes incorporated into diet had little effect on neonate fitness, but may induce subtle physiological changes in later instar larvae. Phenolics, alone or in combination with terpenes, excessively suppressed growth and survival, with no individuals living through the fourth instar, regardless of the nitrogen level. Incorporating foliar phenolic extracts into artificial diet caused unnatural levels of toxicity and failed to clarify the effects of Douglas-fir phenolics on gypsy moth fitness. Foliar nitrogen is a key factor influencing gypsy moth development on Douglas fir, but may be mitigated to some degree by phenolics.
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    URL: http://dx.doi.org/10.1007/BF00987384
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    Nitrogen availability of soluble and slow release nitrogen fertilizers as assessed by electroultrafiltration (1993)
    Springer
    Nutrient cycling in agroecosystems 34 (1993), S. 121-126 
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    ISSN: 1573-0867
    Keywords: Controlled release fertilizers ; electroultrafiltration ; nitrogen ; ryegrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The efficiency of different nitrogenous fertilizers under forced leaching conditions was determined in pot experiments using ryegrass as an indicator plant in a sandy loam soil. Treatments were: ON (unfertilized), AN (ammonium nitrate), U (urea), DAP (diammonium phosphate), T (Triabon), FK (Floranid Komplett) and CDU (crotonylidendiurea). N source effects on N uptake, and N leached (as % of N applied) were evaluated. Results show that the fertilizers which behaved best with regard to N uptake were FK followed by Triabon and AN. The most soluble fertilizers, AN and urea, gave the highest N leaching losses. Significant correlations between EUF-NI (rapidly soluble fraction) and leaching, as well as between EUF-N (I + II) and N uptake by the plant (where EUF-N II relates to the slowly soluble fraction) were obtained.
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    URL: http://dx.doi.org/10.1007/BF00750106
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    Soil nutrient depletion by agricultural production in Southern Mali (1993)
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 79-90 
    Details
    ISSN: 1573-0867
    Keywords: agriculture ; Sahel ; Sudan ; Mali ; cotton ; fertilization ; nutrient ; soil ; soil degradation ; depletion ; nutrient ; nutrient balance ; nitrogen ; phosphorus ; potassium ; calcium ; magnesium ; acidification ; sustainability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The degree of soil mining by agricultural production in Southern Mali is assessed by calculating nutrient balances: differences between the amount of plant nutrients exported from the cultivated fields, and those added to the fields. Export processes include extraction by crops, losses due to leaching, to erosion, and to volatilization and denitrification. Inputs include applications of fertilizer and manure, restitution of crop residues, nitrogen fixation, atmospheric deposition of nutrients in rain and dust, and enrichment by weathering of soil minerals. Nutrient balances are calculated for N, P, K, Ca, and Mg. Both pessimistic and optimistic estimates are given. The resulting figures indicate, even when the most optimistic estimates are used, large deficits for nitrogen, potassium and magnesium. For the region as a whole, the calculated deficits are -25 kg N/ha,-20 kg K/ha, and -5 kg Mg/ha. Further, acidification is to be expected, in particular in areas where cotton is grown. The deficits are caused by traditional cereal crops, but also by cotton and especially by groundnut. The latter two crops are fertilized, but insufficiently. It is important to note, that the negative figures are not automatic recommendations for application of a specific amount of additional fertilizer. For phosphorus and calcium the balance of the region as a whole appears to be about in equilibrium, but locally large variations may occur. Erosion and denitrification are important causes of nutrient loss, accounting respectively for 17 and 22% of total nitrogen exports. Atmospheric deposition and weathering of minerals in the soil are still important nutrient inputs that contribute as much as nutrients as organic and mineral fertilizer combined. Nutrient depletion is very large in comparison to the amount of fertilizer applied. Drastic options, such as doubling the application of fertilizer or manure, or halving erosion losses, even if feasible, would still not be enough to make up for the calculated deficits. The annual value of withdrawn nutrients, if related to prices of fertilizers, varies between 10,000 and 15,000 FCFA/ha (40-60 US $/ha). Since the estimated average gross margin from farming in this area is 34,000 FCFA/ha (123 US $/ha), soil mining appears to provide an amount equal to 40% of farmers' total income from agricultural activities.
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    URL: http://dx.doi.org/10.1007/BF00749951
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    Synthesis of aluminum nitride in transferred arc plasma furnaces (1993)
    Springer
    Plasma chemistry and plasma processing 13 (1993), S. 613-632 
    Details
    ISSN: 1572-8986
    Keywords: Aluminum nitride ; aluminum ; nitrogen ; hydrogen ; ammonia ; thermal plasma ; transferred plasma ; emission spectroscopy ; sintering ; ultrafine powder ; nanophase ; composite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Ultrafine particles of aluminum tnitride (AIN) arc produced by a transferred an plasma. Two devices are used: a transferred arc plasma on aluminum natal in nitrogen or nitrogenlammonia atmospheres, and a item concept of transferred arc plasma when, DC anode and cathode ares are coupled together above an alumintun melt. Equilibrium chemical compositions mere calculated. The temperature distributions in the plasma are measured hr emission spectroscopy Flit, powder, made from 99.8%, aluminum ingot, it as analyzed and confirmed to be 99.3%, of hexagonal phase aluminum nitride. In othertests, from 99.99% aluminum ingot, a translucent AIN vinter was obtained. The densification behavior was assessed by hot pressing and by pressureless sintering, with and without additives. The thermal conductivities are given.
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    URL: http://dx.doi.org/10.1007/BF01570134
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    Nitrogen release from decomposing seaweeds: species and temperature effects (1993)
    Springer
    Journal of applied phycology 5 (1993), S. 175-181 
    Details
    ISSN: 1573-5176
    Keywords: decomposition ; Gracilaria ; nitrogen ; nutrients ; temperature ; Ulva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study determined the rate at which nitrogen accumulated in seaweeds is released during decomposition and the effect of temperature on their rates of decomposition and nitrogen release. Gracilaria verrucosa and Ulva lactuca decomposed rapidly in outdoor mesocosms. Ulva, but not Gracilaria, became nitrogen-enriched during decomposition. Maximal weekly rates of nitrogen release were 5.91 ± 2.23 and 6.37 ± 2.59 g N m−2 d−1, respectively for Gracilaria and Ulva. Temperature had a significant effect on the decomposition rate of Gracilaria in a laboratory experiment: decomposition was greater at 30 °C than at 25 °C. No net decomposition was observed at 16 °C. Gracilaria became nitrogen enriched at 30 °C, but not at 16° or 25°. The release of stored nutrients from decaying seaweeds should be included in nutrient budgets and models when seaweed standing stocks are significant. Seaweed source-sink relationships are important ecologically and can be applied to attempts at using seaweeds as environmental monitors of anthropogenic eutrophication and to efforts of cultivating seaweeds for the improvement of water quality.
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    URL: http://dx.doi.org/10.1007/BF00004014
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    Availability and uptake of inorganic nitrogen in a mixed old-growth coniferous forest (1993)
    Springer
    Plant and soil 148 (1993), S. 163-174 
    Details
    ISSN: 1573-5036
    Keywords: ammonium ; nitrate ; nitrification ; nitrogen ; old-growth forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Old-growth forest stands of mixed species composition provide the opportunity to study species-specific influences on soil properties. We monitored rates of nitrogen mineralization, nitrification and an index of ammonium and nitrate uptake in a mixed old-growth stand of Douglas-fir (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla) and western redcedar (Thuja plicata) over a two-year period. Litter and mineral soil (0–10-cm depth) were sampled adjacent to ten large trees of each species. After initial characterization of litter and soil, buried bags were incubated in both layers for ca. 2-month intervals. Soil and litter pH was lowest near western hemlocks. Nitrification, nitrate concentrations, and percent uptake as nitrate differed among the tree species; rates were highest near western redcedars. For all species, percent nitrification and nitrate uptake rate were higher in soil than in litter. The results indicate species-specific effects on ammonium and nitrate production and uptake within this forest type.
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    URL: http://dx.doi.org/10.1007/BF00012854
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    Leaf expansion, photosynthesis, and water relations of sunflower plants grown on compacted soil (1993)
    Springer
    Plant and soil 149 (1993), S. 175-184 
    Details
    ISSN: 1573-5036
    Keywords: compaction ; Helianthus annuus L. ; leaf expansion ; nitrogen ; osmotic potential ; photosynthesis ; root growth ; soil strength ; turgor ; water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Leaf expansion and growth response of sunflower (Helianthus annuus, L.) to soil compaction were investigated in relation to compaction effects on water relations, nitrogen nutrition, and photosynthesis. A series of field experiments were conducted with plants grown in 20 cm-diameter cylinders with soil bulk densities ranging from 1.2 to 1.7 g cm−3 at the 0–20 cm depth (equivalent to 0.8 to 2.4 MPa soil strength measured with a soil penetrometer). Relative leaf expansion rate (RLER) decreased linearly with increasing soil strength. Smaller plant size in compacted treatments was due not only to slower expansion rates, but also smaller maximum size of individual leaves. Sensitivity of leaf expansion to soil strength was best illustrated by a reduction in RLER and maximum size of the first leaf to emerge in a treatment with only the lower 10–20 cm of the profile compacted (bulk density of 1.7 g cm−3). Root growth was less affected than shoot growth by compaction and root:shoot ratios of compacted treatments were significantly higher than the control. Soil compaction had no significant effect on pre-dawn or midday leaf water potential, osmotic potential or leaf turgor. Specific leaf weight was usually higher in plants grown on compacted soil, and leaf nitrogen and photosynthesis per unit leaf area were either unaffected by treatment or significantly higher in compacted treatments. The results suggest that early growth reduction of sunflower plants grown on compacted soil was more sink- than source-limited with regard to water, nitrogen, and carbon supply. Further evaluation of this hypothesis will require verification that these whole-leaf measurements provided a sufficiently accurate approximation of treatment effects on the dynamic equilibria of expanding cells.
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    Decay rate and substrate quality of fine roots and foliage of two tropical tree species in the Luquillo Experimental Forest, Puerto Rico (1993)
    Springer
    Plant and soil 150 (1993), S. 233-245 
    Details
    ISSN: 1573-5036
    Keywords: decomposition ; fine roots ; lignin ; litterbags ; nitrogen ; polyphenols ; substrate quality ; trees ; tropical montane rain forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Decomposition rates, initial chemical composition, and the relationship between initial chemistry and mass loss of fine roots and foliage were determined for two woody tropical species, Prestoea montana and Dacryodes excelsa, over a gradient of sites in two watersheds in the Luquillo Experimental Forest, Puerto Rico. At all locations, fine roots decayed significantly more slowly than foliage during the initial 6 months. Substrate quality of the initial tissue showed marked differences between roots and foliage when using cell wall chemistry, secondary chemistry and total elemental analysis as indices. Quantity of acid detergent fiber (ADF) (non-digestible cell wall fiber) and lignin content were higher for roots than leaves: D. excelsa roots had 55.3% ADF and 28.7% lignin while leaves had 36.2% ADF and 11.8% lignin; P. montana roots had 68.0% ADF and 26.8% lignin while leaves had 48.5% ADF and 16.1% lignin. Aluminum concentrations were higher in fine roots (843 mg kg−1 in D. excelsa, 1500 mg kg−1 in P. montana) than leaves (244 mg kg−1 in D. excelsa, 422 mg kg−1 in P. montana), while calcium concentrations were higher in foliage (5.5 mg g−1 in D. excelsa, 7.8 mg g−1 in P. montana) than roots (3.4 mg g−1 in D. excelsa, 3.1 mg g−1 in P. montana). Nitrogen did not show any trend with tissue or species type. A linear model between mass remaining after 6 months and initial tissue chemistry could be developed only for calcium (r2=0.64).
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    Methods for measuring biological nitrogen fixation in grain legumes (1993)
    Springer
    Plant and soil 152 (1993), S. 19-23 
    Details
    ISSN: 1573-5036
    Keywords: acetylene reduction ; difference method ; legumes ; 15N isotope method ; nitrogen ; nitrogen fixation ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To assure proper management and fully realize the benefits of the legume-Rhizobium symbiosis it is necessary to be able to quantify the amount of nitrogen fixed. Having measured the effectiveness of atmospheric N2 fixation the macro- or micro-symbionts as well as agronomic factors can be manipulated with the objective to maximize biological nitrogen fixation. A suitable method to quantify nitrogen fixation is therefore necessary in any programme aiming at increasing N2 fixation, like the one being reported in this volume. There are several methods available to quantify nitrogen fixation and most of the commonly used ones are described in the present paper listing their advantages and disadvantages.
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    Variation in 15N enrichment of crimson clover labeled under field conditions (1993)
    Springer
    Plant and soil 152 (1993), S. 255-260 
    Details
    ISSN: 1573-5036
    Keywords: crimson clover ; field labeling ; legume ; nitrogen ; 15N ; variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant material labeled with 15N is often used to determine recovery of N from green manure crops by subsequent crops. In this study, 15N enriched crimson clover (Trifolium incarnatum L.) was grown at a field site where it was to be utilized in a subsequent experiment. A foliar spray of (NH4)2SO4 (99 atom % excess 15N) was applied to a 1.2 m × 8.8 m plot of crimson clover at a rate of 10 kg N ha−1 in early March 1990, immediately prior to the period of rapid vegetative growth. Clover shoots harvested in April contained 1.72 atom % excess 15N. Total N concentration of enriched clover was similar to that in adjacent untreated clover. Clover shoots contained 20% of the applied 15N, and an additional 27% was recovered from the surface soil horizon (0 to 15 cm). A gradient was observed across the plot, with clover enrichment increasing from 1.3 to 2.2 atom % excess 15N. Recovery of applied 15N in soil was highest in the subplots with lowest clover enrichment. Variability in 15N enrichment was also observed among plant parts: leaves from the basal half of shoots had 2.2 atom % excess 15N; while leaves from the terminal half of shoots, terminal stems, and basal stems had between 1.1 and 1.4 atom % excess 15N.
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    Iron-deficiency chlorosis in Scots pine growing on acid soils (1993)
    Springer
    Plant and soil 153 (1993), S. 255-263 
    Details
    ISSN: 1573-5036
    Keywords: acid soil ; chlorosis ; iron deficiency ; nitrogen ; Pinus sylvestris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Scots pine (Pinus sylvestris L.) trees growing on acidic soils may show a special type of chlorosis. The current needles are yellowish and the discolouration is most pronounced at the needle base. The disease bears resemblance to iron chlorosis in trees on calcareous soils. In order to investigate the cause of the chlorosis, needle and soil samples were collected in 41 stands in the southern, central and eastern parts of the Netherlands. Needles of the chlorotic trees had low levels of chlorophylls and carotenoids and high ratios of carotenoids to chlorophylls and of chlorophyll a to chlorophyll b. These symptoms occur in plants suffering from iron deficiency. The current needles of chlorotic trees contained on average 14 mg kg−1 Fe, whereas unaffected trees from the same stands contained 24 mg kg−1. Healthy trees from stands without chlorotic trees had needle iron levels of 29 mg kg−1. Spraying the needles of chlorotic trees with ferric-EDTA containing solutions resulted in partly regreening within a few weeks. Chlorotic needles showed also high nitrogen and cadmium levels. Soils of chlorotic stands contained large amounts of extractable inorganic nitrogen and phosphorus. The possible causal relationships between the observed iron deficiency and the differences in elemental composition of needles and soils are discussed.
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    URL: http://dx.doi.org/10.1007/BF00012998
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    Grain protein and grain yield of tritordeum in comparison to wheat and triticale (1993)
    Springer
    Plant and soil 153 (1993), S. 287-293 
    Details
    ISSN: 1573-5036
    Keywords: grain protein concentration ; grain yield ; nitrogen ; tritordeum ; triticale ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The new species of cereal × Tritordeum Ascherson et Graebner (Hordeum chilense Roem. et Shultz × Triticum ssp.) has a grain protein concentration (GPC) of up to 25%. The relationship between GPC and yield, and the factors responsible for the high GPC of tritordeum were examined and compared in field experiments. Three experimental tritordeum lines, two early and a later released (recombined and secondary tritordeums) were compared to wheat (cv. Cajeme) and triticale cultivars (cv. Trujillo). GPC's were 19%–22% for recombined tritordeums, 16% for the secondary tritordeum, 12–15% for wheats and 11% for triticale. Grain yields of the recombined and secondary tridordeum were 17–33% and 45–57% that of the wheats and triticale, respectively. Reducing grain sink size by spikelet removal resulted in an increased GPC of remaining grains. Considering all species together there were a strong inverse relationship between GPC and grain yield (GY) per main ear (GPC=26−4.76 ln GY; r2=0.82). In another experiment, frost damage to an early sown treatment of wheat reduced sink size. Harvest index (HI) of early sown wheat was reduced from 0.45 to 0.19, values comparable to that of tritordeum. Having similar HI, the GPC of the early sown wheat was the same as an early sown tritordeum (around 18%). Data for total N uptake and the N concentration of plant tissue during the growing season indicated that enhanced N uptake and remobilisation were not responsible for tritordeum's high GPC. These results suggest that the high GPC of the early lines of tritordeum is a consequence of the small grain yield concentrating the grain protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00013002
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    Effects of fertilization levels in two farming systems on senescence and nutrient contents in potato leaves (1993)
    Springer
    Plant and soil 154 (1993), S. 81-88 
    Details
    ISSN: 1573-5036
    Keywords: farming system ; fertilization ; magnesium ; nitrogen ; potassium ; potato ; proteolytic enzymes ; senescence ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of fertilization on senescence and nutrient remobilization in potato leaves was investigated in two farming systems on a soil with a poor potassium availability. The ‘Conventional’ farming system followed good local practices including industrial products, while in the ‘Bio-Dynamic’ farming system industrial fertilizers and synthetic pesticides were avoided. Potassium concentrations in the dry matter of mature leaves varied over a wide range. Nitrogen compounds (protein, chlorophyll) were less affected, and phosphorus concentrations in the dry matter were similar. Magnesium and potassium concentrations in the leaves were negatively correlated. In both farming systems senescence was advanced in plants with a low nutrient supply. Alkaline pyrophosphatase and aminopeptidase activities (in general highest in expanding and mature leaves) were lower and endopeptidase activities peaked earlier on plots with low fertilizer levels. A high percentage of potassium was remobilized from senescing leaves on unfertilized plots, but the phosphorus concentration remained high at the end of the season. The results suggest that the differential net remobilization of nitrogen, phosphorus and potassium depended on actual source/sink relations in the plants.
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    URL: http://dx.doi.org/10.1007/BF00011075
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  • 86
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    Estimates of the residual nitrogen benefit of groundnut to maize in Northeast Thailand (1993)
    Springer
    Plant and soil 154 (1993), S. 267-277 
    Details
    ISSN: 1573-5036
    Keywords: added nitrogen interactions ; groundnut ; maize ; nitrogen ; 15N-isotope methodology ; residual effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four cultivars of groundnut were grown in upland soil in Northeast Thailand to study the residual benefit of the stover to a subsequent maize crop. An N-balance estimate of the total residual N in the maize supplied by the groundnut was made. In addition three independent estimates were made of the residual benefits to maize when the groundnut stover was returned to the land and incorporated. The first estimate (Estimate 1) was an N-balance estimate. A dual labelling approach was used where 15N-labelled stover was added to unlabelled microplots (Estimate 2) or unlabelled stover was added to 15N-labelled soil microplots (Estimate 3). The nodulating groundnut cultivars fixed between 59–64% of their nitrogen (as estimated by the 15N isotope dilution method using non-nodulating groundnut as a non-fixing reference) producing between 100 and 130 kg N ha-1 in their stover. Although the following maize crop suffered from drought stress, maize grain N and dry weights were up to 80% and 65% greater respectively in the plots where the stover was returned as compared with the plots where the stover was removed. These benefits were comparable with applications of 75 kg N ha-1 nitrogen in the form of urea. The total residual N estimates of the contribution of the nodulated groundnut to the maize ranged from 16.4–27.5 kg N ha-1. Estimates of the residual N supplied by the stover and fallen leaves ranged from 11.9–21.3 kg N ha-1 using the N-balance method (Estimate 1), from 6.3–9.6 kg N ha-1 with the labelled stover method (Estimate 2) and from 0–11.4 kg N ha-1 with the labelled soil method. There was closest agreement between the two 15N based estimates suggesting that ‘apparent added nitrogen interactions’ in these soils may not be important and that N balance estimates can overestimate the residual N in crops following legumes, even in very poor soils. This work also indicates the considerable ability of local groundnut cultivars to fix atmospheric nitrogen and the potential benefits from returning and incorporating legume residues to the soil in the upland cropping systems of Northeast Thailand. The applicability of the 15N methodology used here and possible reasons for the discrepancies between estimates 1, 2 and 3 are discussed.
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    URL: http://dx.doi.org/10.1007/BF00012532
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    Changes in the amino acid composition and protein modification in phloem sap of rice (1993)
    Springer
    Plant and soil 155-156 (1993), S. 171-174 
    Details
    ISSN: 1573-5036
    Keywords: amino acid ; nitrogen ; phloem sap ; phosphorylation ; protein ; rice (Oryza sativa L.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Pure phloem sap was collected from insects feeding on rice (Oryza sativa L.) leaves by a laser technique similar to the aphid stylet technique. Rapid circulation of nitrogen in the sieve tubes was demonstrated directly using 15N as a tracer. Application to the roots of the metabolic inhibitors of amino acids, aminooxyacetate and methioninesulfoximine, changed the amino acid composition in the sieve tubes. Feeding methionine to leaf tips resulted in its bulk transfer into the sieve tubes. In vitro experiments confirmed the existence of protein kinases in the pure rice phloem sap. The phosphorylation status of the sieve tube sap proteins was affected by the light regime. The possibility that changes in chemical composition or protein modification such as phosphorylation in the sieve tubes might affect plant growth are discussed. Analysis of pure phloem sap collected from rice plants by insect laser technique has shown dynamic changes in the chemical composition and the quality of proteins in the sap.
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    URL: http://dx.doi.org/10.1007/BF00025011
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  • 88
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    Allocation of carbon and nitrogen as a function of the internal nitrogen status of a plant: Modelling allocation under non-steady-state situations (1993)
    Springer
    Plant and soil 155-156 (1993), S. 183-186 
    Details
    ISSN: 1573-5036
    Keywords: allocation ; carbon ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In this paper we model allocation of carbon and nitrogen to roots and leaves as a function of the nitrogen status of a plant. Under steady-state conditions, allocation of carbon and nitrogen to leaves is exponentially (positively) correlated with plant nitrogen concentration, whereas allocation to roots is correlated negatively, also in an exponential manner. Allocation functions derived under steady-state conditions are used to simulate biomass partitioning under non-steady-state nutrient conditions. Upon nitrogen deprivation, measured and simulated values are rather similar with time, suggesting that allocation functions derived under steady-state conditions also hold under non-steady-state conditions.
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    URL: http://dx.doi.org/10.1007/BF00025014
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  • 89
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    Non-structural carbohydrate: Analysis by near infrared reflectance spectroscopy and its importance as an indicator of plant growth (1993)
    Springer
    Plant and soil 155-156 (1993), S. 243-246 
    Details
    ISSN: 1573-5036
    Keywords: fructans ; NIR ; nitrogen ; non-structural carbohydrates ; rice ; starch ; stress ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant shoot samples are frequently analysed to assess if crops require additional nitrogen or mineral elements to maintain satisfactory growth. If plant growth is limited by temperature, water stress, disease, lodging or a mineral deficiency, non-structural carbohydrates (NSC) may be accumulated in, or depleted from, tissues especially those in the lower stems. Plant testing laboratories do not routinely analyse NSC to assist in the identification of plant stress probably because skilled technicians and time are required for the wet chemical determination. In this paper we report that routine determination of NSC is possible using near-infrared reflectance spectroscopy; the errors of determination are comparable with traditional chemical methods. The concentration of NSC in the shoots of rice grown in south eastern Australia ranges from 1.6 to 22.8%, as starch. In the shoots of wheat grown in eastern Australia the range is from 2.4 to 35.2%, as fructans. In both crops the NSC content is highly inversely correlated with the shoot nitrogen content. Based on data from commercial wheat and rice crops we suggest that the ratio between nitrogen and NSC can be used to identify crops in which growth has been limited by a stress other than nitrogen and so are unlikely to show the predicted response to an application of nitrogen fertilizer.
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    URL: http://dx.doi.org/10.1007/BF00025029
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  • 90
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    Mineral nutrient disorders of root crops of the Pacific: Preliminary observations on sweet potato (Ipomoea batatas) (1993)
    Springer
    Plant and soil 155-156 (1993), S. 263-267 
    Details
    ISSN: 1573-5036
    Keywords: critical concentration ; magnesium ; manganese ; nitrogen ; phosphorus ; potassium ; solution culture ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Solution culture was used to characterise deficiencies or toxicities of several essential elements in Ipomoea batatas cv. Wanmun, and to define the critical concentrations of these elements in young mature leaves during vegetative growth. Tentative critical concentrations for deficiency, expressed on the basis of dry weight of leaf blade, were: nitrogen 3.8%, phosphorus 0.17%, potassium 2.4%, magnesium 0.12%, manganese 20μg/g and zinc 10μg/g. For manganese and zinc toxicities it was possible only to designate the range within which the critical concentration occurred. Visible symptoms are briefly described.
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    URL: http://dx.doi.org/10.1007/BF00025033
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  • 91
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    A comparison of the effects of subsoiling on plant uptake and leaching losses of sulphur and nitrogen from a simulated urine patch (1993)
    Springer
    Plant and soil 155-156 (1993), S. 375-378 
    Details
    ISSN: 1573-5036
    Keywords: clover ; grass ; leaching ; lysimeter ; nitrogen ; 15N ; nutrient balances ; nutrient uptake ; pasture ; subsoiling ; sulphur ; 35S
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Synthetic cow urine labelled with 35S and 15N was applied to large, undisturbed, monolith lysimeters sampled from subsoiled and non-subsoiled areas of a grass/clover pasture. For one year following the urine application, the lysimeters were subjected to a combination of natural rainfall, simulated rainfall and simulated flood irrigations. Drainage from the lysimeters was sampled regularly and monthly (approx.) pasture cuts taken. At the end of the year, the lysimeters were destructively sampled in 50 mm depth increments for soil analysis. Leachates, plant samples and soil samples were analysed for 35S and 15N. There were no significant differences in plant uptake of 35S and 15N between the subsoiled and nonsubsoiled lysimeters. Initially grass showed a higher degree of labelling than clover. Total amounts of 35S and 15N leached from the subsoiled lysimeters were approximately twice that leached from the nonsubsoiled ones. Leaching patterns differed substantially between the two nutrients. Total recoveries of 35S (in plants, leachates and soil extracts) accounted for 82% of the applied 35S for the subsoiled lysimeters and 72% for non-subsoiled ones. The unrecovered 35S is considered to have been incorporated into soil organic matter. Total recoveries of 15N (in plants, soil and leachates) were similar to those for 35S, but unrecovered 15N is attributed to loss by denitrification.
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    URL: http://dx.doi.org/10.1007/BF00025061
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  • 92
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    Effects of sowing time and plant age on critical nitrogen concentrations in canola (Brassica napus L.) (1993)
    Springer
    Plant and soil 155-156 (1993), S. 387-390 
    Details
    ISSN: 1573-5036
    Keywords: Brassica napus L. ; canola ; critical concentrations ; nitrate ; nitrogen ; sowing time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Critical concentrations of NO3-N in fresh petiole tissue and total N in the dried lamina were determined for the youngest mature leaf (YML) of field-grown canola. For dry matter yield of canola sown on 4 May, critical NO3-N concentration in the YML petiole at the rosette stage (RS) was 1.46 mg/g fresh wt. At the flower-buds-visible stage (BV) it was 0.45 mg/g fresh wt. For seed yield the values were 1.72 and 0.53 mg/g fresh wt. Critical total N concentration in the YML lamina for dry matter yield were 69 mg/g dry wt. at RS and 57 at BV. For seed yield they were 71 and 59 mg/g dry wt. Critical NO3-N concentrations in the YML petiole of canola sown on 30 May were reduced by 50%; critical total-N concentrations in the YML lamina were not reduced to the same extent. Despite the reductions in critical N concentrations in the YML, critical N fertilizer rates for vegetative growth and seed yield were unaffected by sowing date or plant growth stage.
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    URL: http://dx.doi.org/10.1007/BF00025064
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    Nuclear magnetic resonance studies of the location and function of plant nutrients in vivo (1993)
    Springer
    Plant and soil 155-156 (1993), S. 45-55 
    Details
    ISSN: 1573-5036
    Keywords: compartmentation ; cytoplasm ; 39K NMR ; maize ; nitrogen ; 14N NMR ; 15N NMR ; pea ; phosphorus ; potassium ; 31P NMR ; vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The cytoplasmic and vacuolar pools of ammonium, inorganic phosphate and potassium can be studied non-invasively in plant tissues using high resolution nuclear magnetic resonance spectroscopy. The techniques that allow these pools to be discriminated in vivo are described and their application to plants is reviewed with reference to the phosphorus, nitrogen and potassium nutrition of root tissues.
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    URL: http://dx.doi.org/10.1007/BF00024983
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    Molecular biological approaches to plant nutrition (1993)
    Springer
    Plant and soil 155-156 (1993), S. 21-31 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; sulphur-nutrition ; gene cloning ; gene expression ; regulation ; crop improvement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the last decade, understanding of ion transport has grown sufficiently to pose sensible questions about the molecular nature of the processes and their regulation. Techniques for identifying and cloning genes and for genetic transformation provide the means for answering these questions. Transport of ions across membranes is obviously a major aspect of mineral nutrition since it occurs during initial absorption, compartmentation and mobilisation of nutrients. Here, we will briefly review the types of transport protein involved and show how molecular biology and recombinant DNA technology have revealed something of their structure. Strategies used to identify the genes for transporters are discussed and reference is made to areas in which the availability of cloned genes will facilitate future studies. Mineral nutrition involves, however, more than membrane transport. The absorption rates of major nutrients are quite strictly regulated by biochemical factors which vary with the rate at which nutrients are used in growth. Nitrogen, sulphur and phosphate nutrition in micro-organisms are regulated by the interaction of various DNA-binding proteins with the promoter regions of genes for key enzymes in the assimilatory pathways and the specific ion permeases. The expression of the regulatory protein or its activity can be modified by metabolites, such as glutamine. Some evidence supports the idea that higher plants also have groups of genes with a common regulation of expression. An attempt is made to identify some reasonable objectives, which should increase understanding of the regulation of nutrient transport.
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    URL: http://dx.doi.org/10.1007/BF00024981
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    Modelling nutrient responses in the field (1993)
    Springer
    Plant and soil 155-156 (1993), S. 57-66 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; wheat ; simulation ; yield-response curve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Models of the yield responses of crops to applied nutrients are a recent addition to the methods available for making fertilizer recommendations. They have a place in integrating nutrient information with information on other factors which affect yield and its response to added nutrients. This review deals with nitrogen models classified into three groups: those which predict yield-response curves based on empirical factors; those which simulate the yield response from complex simulation models of many processes regulating crop growth and the soil environment; and those which aim to simulate yield and selected processes based on simplified functional relationships which apply to a target region or industry. Three case studies representing the three classes of model are drawn from research on dryland wheat in different parts of Australia. They show examples in which models provide information which is unobtainable from experimental procedures and which provide information useful to farmers in making decisions about fertilizers. Suggestions are made for future developments in crop-nutrient modelling including further comparisons of models, linkage of models with tissue tests, modelling co-limiting nutrients, deciding on the appropriate level of detail within a model and the need for methods for calibrating and testing models on attributes other than yield alone.
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    URL: http://dx.doi.org/10.1007/BF00024984
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    Estimation of potentially mineralisable nitrogen in soil by KCl extraction (1993)
    Springer
    Plant and soil 157 (1993), S. 167-174 
    Details
    ISSN: 1573-5036
    Keywords: extraction ; mineralisation ; nitrogen ; potassium chloride ; uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The mineral nitrogen extractable from 12 Scottish arable soils by boiling for 1 hour with 1 M KCl solution was compared with the quantities taken up by ryegrass, barley and oats in pot tests. High correlations were obtained for ryegrass and oats (r2=0.85 and 0.79, respectively), with a slightly lower correlation (r2=0.64) for barley. When the results for one anomalous soil were eliminated from the analysis, all r2 values were 0.81 or higher. The results confirmed earlier work indicating that this method may prove useful for predicting crop uptake of soil-derived nitrogen.
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    URL: http://dx.doi.org/10.1007/BF00011045
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    Estimation of potentially mineralisable nitrogen in soil by KCl extraction (1993)
    Springer
    Plant and soil 157 (1993), S. 175-184 
    Details
    ISSN: 1573-5036
    Keywords: barley ; extraction ; malting quality ; mineralisation ; nitrogen ; 15N-labelling ; potassium chloride ; uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The potentially mineralisable nitrogen extracted from 10 soils by two methods involving boiling with dilute KCl were compared with the actual uptake of soil N by spring barley in the field, as determined with the use of 15N-labelled fertiliser. Generally good correlations were found for those soils which had previously been cropped with cereals (defined in Great Britain as either ‘N-Index zero’, or ‘low nitrogen status’ soils, for fertiliser recommendations), with the results obtained by the more severe of the two methods being somewhat better than by the other method. When organic matter content was also taken into account, correlations were improved. Mineral nitrogen in the soil at sowing was highly correlated with potentially mineralisable nitrogen, and with uptake, but this relationship did not hold for soil samples taken in January, well before the likely sowing date. This suggested that early measurement of soil mineral nitrogen (when decisions on cropping are normally made) was not a practicable method for determinining spring fertiliser applications, and that the measure of potentially mineralisable nitrogen appeared more promising in this regard.
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    URL: http://dx.doi.org/10.1007/BF00011046
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    Culture ofGelidium sesquipedale (Clem.) Born.et Thur. in a chemostat system. Biomass production and metabolic responses affected by N flow (1993)
    Springer
    Journal of applied phycology 5 (1993), S. 405-415 
    Details
    ISSN: 1573-5176
    Keywords: agar ; C:N ratio ; chemostat ; Gelidium ; nitrogen ; phycobiliproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gelidium sesquipedale is the most important raw material used for extraction of agar in Spain. Based on chemostats, a system of culture for macroalgae with a continuous flow of culture medium has been developed. A stressed morphotype from the South of Spain was cultured, and the effects of different rates of NO 3 − flow on growth and internal constituents were investigated in the laboratory. Cultivation was successful after optimizing factors affecting growth, such as irradiance level, renewal rate and water movement. Mass production was dependent on N supply. With a flow of 35 μmol NO3 − g−1 DW d−1, optimal values of growth (2.1% d−1) and biomass yield were obtained. In these conditions, biomass yield resembled the values observed in natural populations (about 500 g DW m−2 y−1). When the flow of N was reduced to 15 μmol NO 3 − g−1 DW d−1, growth rate and biomass yield were reduced three-fold, and were null when N was supplied as 7 μmol NO 3 − g−1 DW d−1. C:N ratio was an index of the physiological status of the tissue, remaining low when N was sufficient and raised to critical values when N supply was limited. Phycobiliproteins, kept at a constant irradiance level, were affected by N supply, acting as an internal nitrogen reserve, unlike chlorophylla. An effective phycobiliprotein synthesis took place when the flow of N was sufficient. Agar yield, on dry weight basis, was similar as a function of N flow, whereas agar yield of the culture was higher when N was sufficient as a result of growth not being limited by N. This system of culture, commonly used in microalgal studies, may have an important use in macroalgae as a system to obtain biomass of high quality as well as a good tool for physiological studies in conditions of continuous and controlled flow of nutrients.
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    URL: http://dx.doi.org/10.1007/BF02182733
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    Effect of light intensity and ammonium-N on carotenogenesis ofTrentepohlia odorata andDunaliella bardawil (1993)
    Springer
    Journal of applied phycology 5 (1993), S. 547-549 
    Details
    ISSN: 1573-5176
    Keywords: Trentepohlia odorata ; Dunaliella bardawil ; light intensity ; nitrogen ; growth ; carotenogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract AxenicTrentepohlia odorata was cultured at three different NH4Cl levels (3.5 × 10−2, 3.5 × 10−3, 3.5 × 10−4 M) and three different light intensities (48, 76, 122 µmol m−2 s−1). Chloride had no effect on growth over this range of concentration. High light intensity and high NH4Cl concentration enhanced the specific growth rate. The carotenoid content increased under a combination of high light intensity and low N concentration. WhenD. bardawil was exposed to the same combination of growth conditions, there was an increase in its carotenoid content. The light saturation and the light inhibition constants (K s andK i, respectively) for growth, and the saturation constant (K m) for NH4Cl were determined. TheK s andK i values were higher inT. odorata (66.7 and〉 122 σmol m−2 s−1, respectively) than inD. bardawil (5.1 and 14.7 µmol m−2 s−1, respectively). TheK m value determined at 122 µmol m−2 s−1, however, was lower inT. odorata (0.048 µM) than inD. bardawil (0.062 µM).
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    URL: http://dx.doi.org/10.1007/BF02182515
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  • 100
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    Contribution of inoculation with azolla combined with nitrogen, phosphorus and zinc to rice in Nile Delta (1992)
    Springer
    World journal of microbiology and biotechnology 8 (1992), S. 579-584 
    Details
    ISSN: 1573-0972
    Keywords: Azolla ; fertilization ; nitrogen ; phosphate ; rice ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Rice performance, in terms of plant height, productive tillering, yield and N-contents of grain and straw, harvest index (grain yield as a percentage of grain plus straw yields) and relative fertilizer N-use efficiency (kg grain yield/kg fertilizer-N) was enhanced by urea, ZnSO4 and green manuring withAzolla caroliniana. Unlike urea fertilizer, calcium superphosphate increased the rate of azolla field colonization and promoted a thick, healthy dark-green mat of the fern. Response to ZnSO4 was higher in the azolla-free sub-subplots. Application of ZnSO4 corrected symptoms of Zn deficiency in rice but the addition of calcium superphosphate in the absence of Zn intensified the symptoms of Zn deficiency.
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    URL: http://dx.doi.org/10.1007/BF01238792
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