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  • 1
    Electronic Resource
    Electronic Resource
    Contribution of nitrogen and phosphorus by precipitation in the drainage basin of the Santillana Reservoir (Madrid) (1994)
    Springer
    Environmental geology 23 (1994), S. 99-104 
    Details
    ISSN: 1432-0495
    Keywords: Nitrogen ; phosphorus ; Precipitation collector ; Nutrients rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The contribution of nitrogen and phosphorus due to precipitation constitutes the second most important route after superficial runoff. The sampling carried out during a two-year period by means of a precipitation collector allows us to determine the contribution of this route both qualitatively and quantitatively. Nitrogen is mainly supplied in an inorganic form, while phosphorus is principally supplied as orthophosphate. During the period of this study (March 1986–February 1988) it was found that in the Santillana Reservoir Watershed the level of nitrogen supplied by precipitation constitutes an average of 4.87% and the level of phosphorus constitutes 8.01%. The contribution of nitrogen varies in inverse ratio to precipitation and the contribution of phosphorus varies in direct ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00766982
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  • 2
    Electronic Resource
    Electronic Resource
    Distribution and sources of phosphorus in tidal river sediments in the Washington, DC, Area (1997)
    Springer
    Environmental geology 30 (1997), S. 224-230 
    Details
    ISSN: 1432-0495
    Keywords: Key words Sediment ; Washington ; DC ; Pollution ; phosphorus ; nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Sediments in the rivers and basins around Washington, DC, have high concentrations of phosphorus, which, based on geographic distributions, is largely derived from urban runoff and municipal sewage. Dissolved-particulate phosphate exchange reactions and biological uptake of dissolved phosphorus from the water column may be an added source of phosphorus to the sediments. Concentrations of total sedimentary phosphorus ranged from 24 to 56 μm P/g-dw, and were highest in areas near combined sewer outfalls. As a part of this study, sedimentary phosphorus was fractionated into Fe-P, Ca-P, Al-P, and organic phases using a selective-sequential leaching procedure. The distribution of the phases in all sediments analyzed follow the order , Fe-P〉Ca-P〉Al-P. Spatial variations in the amounts of phosphorus in the different phases is related to the sources of phosphorus to the area. The proportions of occluded Al-P and organic P are 10–20% of the total P, respectively. This suggests that phosphorus from natural sources is small compared to anthropogenic inputs in this area. The high leachable Fe-P and Ca-P in these sediments might contribute a substantial amount of P to the water column under conditions of remobilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002540050150
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of repeated manure and fertilizer phosphorus additions on soil phosphorus dynamics under a soybean-wheat rotation (1999)
    Springer
    Biology and fertility of soils 28 (1999), S. 150-155 
    Details
    ISSN: 1432-0789
    Keywords: Key words Phosphorus dynamics ; Olsen ; phosphorus ; Soil phosphorus fractions ; Manure ; Soybean-wheat rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Soil P availability and efficiency of applied P may be improved through an understanding of soil P dynamics in relation to management practices in a cropping system. Our objectives in this study were to evaluate changes in plant-available (Olsen) P and in different inorganic P (Pi) and organic P (P0) fractions in soil as related to repeated additions of manure and fertilizer P under a soybean-wheat rotation. A field experiment on a Typic Haplustert was conducted from 1992 to 1995 wherein the annual treatments included four rates of fertilizer P (0, 11, 22 and 44 kg ha–1 applied to both soybean and wheat) in the absence and presence of 16 t ha–1 of manure (applied to soybean only). With regular application of fertilizer P to each crop the level of Olsen P increased significantly and linearly through the years in both manured and unmanured plots. The mean P balance required to raise Olsen P by 1 mg kg–1 was 17.9 kg ha–1 of fertilizer P in unmanured plots and 5.6 kg ha–1 of manure plus fertilizer P in manured plots. The relative sizes of labile [NaHCO3-extractable Pi (NaHCO3-Pi) and NaHCO3-extractable P0 (NaHCO3-P0)], moderately labile [NaOH-extractable Pi (NaOH-Pi) and NaOH-extractable P0 (NaOH-P0)] and stable [HCl-extractable P (HCl-P) and H2SO4/H2O2-extractable P (resisual-P)] P pools were in a 1 : 2.9 : 7.6 ratio. Application of fertilizer P and manure significantly increased NaHCO3-Pi and -P0 and NaOH-Pi, and -P0 fractions and also total P. However, HCl-P and residual-P were not affected. The changes in NaHCO3-Pi, NaOH-Pi and NaOH-P0 fractions were significantly correlated with the apparent P balance and were thought to represent biologically dynamic soil P and act as major sources and sinks of plant-available P.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050477
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  • 4
    Electronic Resource
    Electronic Resource
    Oxidation behavior of sintered 434L ferritic stainless steel-Al2O3 composites with ternary additions (1985)
    Springer
    Oxidation of metals 23 (1985), S. 177-189 
    Details
    ISSN: 1573-4889
    Keywords: sintered ferritic stainless steel composite ; porosity ; transition metals ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of sintered ferritic stainless steel-Al2O3 composites, and composites with ternary additions such as titanium, niobium, or phosphorus, have been studied at 550°C in 1 atm oxygen up to 9 hr. It is found that α-SS-6 vol.% Al2O3 is most resistant to oxidation amongst all the compacts investigated. Amongst the ternary composites, niobium-containing compacts show better oxidation resistance compared to titanium or phosphorus-containing composites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00659902
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  • 5
    Electronic Resource
    Electronic Resource
    XRD Investigations of the Phosphorus Effect on the Oxidation of TiAl Alloys by High-Resolution Methods (2000)
    Springer
    Oxidation of metals 54 (2000), S. 317-337 
    Details
    ISSN: 1573-4889
    Keywords: TiAl ; oxidation ; phosphorus ; microdiffraction ; doping ; rutile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recently it has been found that very small amounts (a few 100 ppm) of Padded to γ -titanium aluminide can significantly alter the oxidationbehavior between 973 and 1273 K. The mechanism responsible for this changeis, however, still not clear. In the present study, phosphorus wasincorporated into the surface of TiAl (containing 50 at.% Al) by ionimplantation and oxidation tests were carried out at 1173 K inair. Improvement of oxidation resistance is only temporary up to 100 hr forphosphorus-implanted TiAl. After 100 hr, the oxidation rate increases andbreakaway oxidation follows. XRD and EPMA showed that the breakawayoxidation is connected with massive nitride formation. Two different modelsare proposed which can explain the effect of phosphorus additions on theoxidation kinetics of TiAl during the protective stage within the first100 hr. The breakaway effect can be explained by penetration of air to themetal–oxide interface zone because of microcrack formation in theoxide scale, which was experimentally proved by acoustic-emission analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004606513758
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  • 6
    Electronic Resource
    Electronic Resource
    Response of mango (Mangifera indica L) to foliar application of phosphorus (1983)
    Springer
    Nutrient cycling in agroecosystems 4 (1983), S. 281-285 
    Details
    ISSN: 1573-0867
    Keywords: mango ; foliar spray ; orthophosphoric acid ; phosphorus ; urea ; utilisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Orthophosphoric acid (0.5%) was sprayed along with and without 2 per cent urea on the mango (Mangifera indica L) cv. Langra trees in the months of September, November or March as well as in all the three months. There was an improvement of fruit set in the sprayed treatments which was high after March sprays. Significantly higher yields were obtained in triple spray treatments along with urea. The percentage of phosphorus in the fruits was raised by the sprays. The yield of phosphorus in the fruits was highest in March spray treatment and progressively less in November and September spray treatments. It was concluded that the urea given along with phosphorus improved the utilisation of phosphorus in the fruits by providing a better balance of nutrients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01049484
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  • 7
    Electronic Resource
    Electronic Resource
    Leaching of nitrogen and phosphorus from rural areas to surface waters in the Netherlands (1998)
    Springer
    Nutrient cycling in agroecosystems 50 (1998), S. 321-324 
    Details
    ISSN: 1573-0867
    Keywords: nutrient modelling ; leaching ; nitrogen ; phosphorus ; schematization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In context of preparing the Fourth National Policy Document on Water Management in the Netherlands effects of different scenarios of fertilizer management on nitrogen (N) and phosphorus (P) leaching from rural areas into Dutch surface waters were analyzed. The manuscript offers insight into the model instrument that is used to simulate the different scenarios. Main parts of the modelinstrument are: a procedure to schematize the Netherlands in horizontal areal units, field scale mechanistic models for water and nutrient behaviour in the soil and an empirical model for fertilizer additions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009773202654
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  • 8
    Electronic Resource
    Electronic Resource
    Morphology of the oral mucosa in rats exposed to high concentrations of phosphorus (1986)
    Springer
    Bulletin of experimental biology and medicine 101 (1986), S. 135-138 
    Details
    ISSN: 1573-8221
    Keywords: phosphorus ; oral mucosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00836099
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of diazotrophic bacteria isolated from a mycelium of arbuscular mycorrhizal fungi on colonization of maize roots by Glomus fistulosum (1998)
    Springer
    Biologia plantarum 41 (1998), S. 617-621 
    Details
    ISSN: 1573-8264
    Keywords: bacterial isolates ; grasses ; mycorrhizal colonization ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The inoculation of mycorrhizal maize plants with three isolates of microaerophilic diazotrophic bacteria obtained from the mycelium of arbuscular mycorrhizal fungi associated with three grasses (Arrhenatherum elatius - bacterial isolate ARR, Agropyrum repens - isolate AGR and Poa annua - isolate POA) caused no increase in nitrogen content in plant biomass. The inoculation with bacterial isolate ARR resulted in the decreased plant growth. Bacterial isolate AGR decreased the percentage of the root length colonized by arbuscular mycorrhizal fungus Glomus fistulosum. The inoculation with both mycorrhizal fungus and isolate POA increased significantly the concentration of phosphorus in plant shoots compared to uninoculated control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1001813004776
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  • 10
    Electronic Resource
    Electronic Resource
    The Role of Plant Size and Nutrient Concentrations in Associations between Medicago, and Rhizobium and/or Glomus (2000)
    Springer
    Biologia plantarum 43 (2000), S. 221-226 
    Details
    ISSN: 1573-8264
    Keywords: alfalfa ; arbuscular mycorrhizal fungi ; nitrogen ; nitrogen-fixing bacteria ; phosphorus ; plant growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The aim of this research was to carry out a critical study of the method of obtaining size equivalence between non-symbiotic alfalfa and alfalfa associated with Glomus and/or Rhizobium by applying fixed addition rates of nutrients to the non-symbiotic controls. The experimental design included three nutrient response curves in which the levels of added phosphorus and/or nitrogen were constant during the whole plant growth process: 1) a phosphorus response curve, in order to compare the growth of double symbiotic plants with that of only-Rhizobium inoculated ones; 2) a nitrogen response curve, that consisted of a comparison between the growth of double symbiotic alfalfa and four treatments associated only with Glomus; 3) a phosphorus and nitrogen response curve, to compare the growth of non-inoculated alfalfa with that of double symbiotic plants. Although similar size was achieved among some treatments at harvest, shoot growth over time and nutrient concentrations in tissues differed, indicating that growth equivalence did not mean functional equivalence. A second experimental design was performed taking into account the establishment of microsymbionts for determining the adequate moment to add supplemental phosphorus and/or nitrogen. It included four treatments: a) double symbiotic plants (MR); b) plants inoculated with Rhizobium only (R); c) plants inoculated with Glomus only (M), and d) non-inoculated plants (N). Great similarity in terms of plant growth and nutrient contents in tissues were obtained. Moreover, symbiotic plants were able to produce similar dry matter than non-symbiotic ones under P and N limitations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002700226167
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  • 11
    Electronic Resource
    Electronic Resource
    Determination of orthophosphate in highly saline waters (1994)
    Springer
    International journal of salt lake research 3 (1994), S. 159-173 
    Details
    ISSN: 1573-8590
    Keywords: phosphorus ; orthophosphate ; phosphomolybdenum blue ; salt effect ; hypersaline ; saline ; lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Standard methods for the determination of phosphorus as phosphate ion are now well established for fresh and marine waters. In highly saline waters, however, salt effects due to ionic strength, or to particular ions present, may result in method interferences. Three methods of analysis of phosphate based on the formation of phosphomolybdenum blue complexes have been evaluated here for hypersaline waters. Stannous chloride reduction in aqueous media exhibits a substantial salt effect and its use is not recommended. Stannous chloride reduction following extraction into non aqueous solvents shows a significant salt effect (up to 30 per cent) in solutions of salinity 〉100 g L−1. Dilution of hypersaline waters to below this salinity may overcome the salt effect but the method suffers from other disadvantages involving resource constraints and health and safety considerations. Ascorbic acid reduction, catalysed by antimony (III) ions, appears to offer the most promise for hypersaline waters. Turbidity in samples having high salinity (〉 100 g L−1) and high phosphorus concentrations (〉 500 μg P L−1) changes the spectral characteristics of solutions but linear calibration curves still result for concentrations in the range 400 to 1,000 μg P L−1. The occurrence of turbidity is also affected by the ionic composition of hypersaline waters since solutions made from sea salt give different results to those made from sodium chloride. Dilution of samples, to give salinities less than 100 g L−1 prior to reduction is recommended to avoid turbidity. The salt effect in these lower salinity waters is less than 3 per cent up to 100 g L−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01990492
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  • 12
    Electronic Resource
    Electronic Resource
    Determination of P/Al ratio in phosphorus-doped aluminium oxide thin films by XRF, RBS and FTIR (1995)
    Springer
    Microchimica acta 119 (1995), S. 13-22 
    Details
    ISSN: 1436-5073
    Keywords: aluminium oxide ; phosphorus ; XRF ; RBS ; FTIR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Phosphorus-doped aluminium oxide thin films were deposited in a flow-type ALE reactor from AlCl3, H2O and from either P2O5 or trimethyl-phosphate. Structural information of the films was obtained from Fourier transform infrared (FTIR) spectra. Rutherford backscattering spectroscopy (RBS) was used to quantitatively determine the composition of the films. The P/Al intensity ratios calculated from X-ray fluorescence (XRF) results were in a linear relation with the P/Al concentration ratios calculated from RBS results. For comparison, the intensity ratios of the phosphorus peak (P=O) at about 1250 cm−1 and the aluminium peak (Al-O) at about 950 cm−1 were determined from the IR absorption spectra. The calibration of FTIR peak intensities was done by plotting the intensity ratios of phosphorus and aluminium peaks against the P/Al concentration ratios measured by RBS. FTIR gave also a linear calibration curve with RBS but the method is less suitable for routine analysis of P/Al ratio than XRF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01244850
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  • 13
    Electronic Resource
    Electronic Resource
    Determination of phosphorus, sulfur and chlorine in high-purity aluminium (1990)
    Springer
    Microchimica acta 101 (1990), S. 273-279 
    Details
    ISSN: 1436-5073
    Keywords: aluminium analysis ; phosphorus ; sulfur ; chlorine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Multi-step procedures for the determination of phosphorus, sulfur and chlorine are described and tested against established methods and on reference materials. Phosphorus is separated as hydrogen phosphide, extracted as phosphomolybdic acid, reduced to molydenum blue and measured photometrically (detection limit 0.05 μg/g). Sulfur is separated after reduction as hydrogen sulfide or by means of pyrohydrolysis and measured by ICP-OES (detection limit 0.1 μg/g). Chloride can be measured by ion chromatography after pyrohydrolytic separation (detection limit 0.1 μg/g). The determination of sulfur was also successfully tested on copper and steel samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01244179
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  • 14
    Electronic Resource
    Electronic Resource
    Seasonal dynamics of a cyanobacteria-dominated microbial community in surface sediments of a shallow, eutrophic lake (1989)
    Springer
    Aquatic sciences 51 (1989), S. 153-178 
    Details
    ISSN: 1420-9055
    Keywords: sediments ; cyanobacteria ; Microcystis ; bacterial biomass ; bacterial production ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seasonal variation of microbial biomass and activity in the surface sediments (0–10 cm) of the shallow, eutrophic Lake Vallentunasjön was followed during one year. “Overwintering”Microcystis colonies dominated the microbial community during all seasons, constituting 60–90% of the total microbial biomass. Expressed on an areal basis, the benthic biomass was, throughout the year, larger than or similar to the planktonic biomass during the peak of the summer bloom, indicating an ability of the colonies to survive in the sediments for extended periods. Abundance of “other”, non-photosynthetic bacteria varied in the range 3.0–15.5 · 1010 cells g−1 d. w. over the year with minimum values in summer and maximum values in autumn in connection with the sedimentation of theMicrocystis bloom. A substantial part of the non-photosynthetic bacteria, up to circa 40%, was associated with the mucilage of healthyMicrocystis colonies. Bacterial production (3H-thymidine incorporation) appeared to be strongly temperature dependent and less influenced by the seasonal sedimentation pattern. Our data indicate an increasing proportion of non-growing cells in autumn and winter. Biomass-bound phosphorus constituted a significant portion, circa 10%, of the phosphorus content in Lake Vallentunasjön sediments. This pool has normally been overlooked in studies on phosphorus dynamics in lake sediments. Different mechanisms whereby organic phosphorus can be released from the sediments are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879300
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  • 15
    Electronic Resource
    Electronic Resource
    Vertical mixing in Überlinger See, western part of Lake Constance (1990)
    Springer
    Aquatic sciences 52 (1990), S. 256-268 
    Details
    ISSN: 1420-9055
    Keywords: Vertical mixing ; stratification ; phosphorus ; Lake Constance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Depth variable vertical eddy diffusion coefficients for heat (K z) were calculated from continuously measured temperature profiles in Überlinger See (western part of Lake Constance). The temperatures were averaged over vertical intervals of 10 m yielding 14 discrete values (maximum depth of Überlinger See: 147 m). A linear fit from 10 June to 29 September 1987 was used to smooth the significant temperature fluctuations caused by internal seiches of Lake Constance. Assuming horizontal homogeneity for the smoothed data the Gradient-Flux-Method was applied to compute vertical diffusion coefficientsK z at different depths using the depth variable volumes and surfaces of the 14 layers. The resulting mean diffusion coefficients for the period from June to September are 0.04 cm2/s near the thermocline and up to 0.8 cm2/s in deeper strata (accuracy: ± 50%). It is shown that horizontal mixing between Überlinger See and Obersee (main lake) alters the computation ofK z by less than 50%. A relationship betweenK z and stability (Brunt-Väisälä) frequencyN is found which corresponds well to the theory of internal wave induced turbulence. Combining the diffusion coefficients with measured phosphorus profiles, a phosphorus flux from the hypolimnion to the epilimnion of (0.7 ± 0.4) mg P m−2 d−1 was calculated, corresponding to about 20% of the average external loading per area of Lake Constance in 1986.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877283
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  • 16
    Electronic Resource
    Electronic Resource
    Effect of snow and soil frost melting on the concentrations of suspended solids and phosphorus in two rural watersheds in Western Finland (1989)
    Springer
    Aquatic sciences 51 (1989), S. 211-223 
    Details
    ISSN: 1420-9055
    Keywords: Particles ; phosphorus ; watersheds ; snow ; frost ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hydrological processes are known to have a considerable effect on nutrient transport from agricultural land to watercourses. In cold temperate regions peak discharges are caused not only by storm conditions but also by melting of snow and frost. The objective of this work was to investigate the effects of snow and frost melt on concentrations of phosphorus and suspended solids. The samples were taken using flowweighted automatic sampling techniques from two agricultural drainage basins. During the beginning of the snowmelt period the concentration of suspended solids was rather low by comparison with the total phosphorus concentration and the discharge. The different behaviour compared with the relationships found during storm conditions was probably caused by continuous extraction of the soil surface by low ionic concentration melt water, and to some extent by leaching from plant residues. The gradual decrease of total phosphorus concentration during the frost thawing period could be attributed to the gradually increasing proportion of the subsurface and ground water discharge in the runoff.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877743
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  • 17
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    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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  • 18
    Electronic Resource
    Electronic Resource
    Measurement of total dissolved phosphorus in small volumes of iron rich interstitial water (1992)
    Springer
    Aquatic sciences 54 (1992), S. 1-9 
    Details
    ISSN: 1420-9055
    Keywords: Sediment ; interstitial water ; phosphorus ; iron ; persulfate digestion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It is shown that sorption of orthophosphate to iron compounds, formed during persulfate digestion, can cause a significant underestimation of total dissolved phosphorus in interstitial waters rich in iron and poor in phosphorus. Labelling the samples with carrier free32PO4 before digestion allows to correct for these losses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877261
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  • 19
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    Possibilities and limitations of lake restoration: Conclusions for Lake Lugano (1992)
    Springer
    Aquatic sciences 54 (1992), S. 381-390 
    Details
    ISSN: 1420-9055
    Keywords: Eutrophication ; phosphorus ; lake restoration ; internal restoration measures for lakes ; Swiss lakes ; Lake Lugano (Lago di Lugano)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In most lakes eutrophication is linked to an excessive input of phosphorus. Lake restoration by reduction of P-input (external measure) has led to a considerable drop of the P-concentration in all major Swiss lakes as well as in many other lakes. Internal restoration measures such as artificial mixing, drainage of hypolimnetic water, flushing, aeration, biomanipulation and others serve to improve and accelerate the response of a lake to external measures. For the case of Lago di Lugano, a simple two-box model is employed to demonstrate that a reduction of the P-input to about 25% of the present values is necessary to reach the “P-criterion” (P-concentration below 30 µg/l). Internal measures could possibly accelerate the extremely slow response of the northern basin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00878149
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  • 20
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    The ecosystem of a mesotrophic lake-II. Interactions among nutrient load, river flow, and epilimnion depth (1991)
    Springer
    Aquatic sciences 53 (1991), S. 263-272 
    Details
    ISSN: 1420-9055
    Keywords: Lake ecosystem ; chl-a ; phosphorus ; nitrogen ; river flow ; thermocline ; simulation model ; multiple regression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The management variables which primarily affect phytoplankton biomass (as chl-a) in Lake Mjøsa, Norway, are total phosphorus loading (TP) and the timing and volume of water through flow (by active storage reservoirs). The response of the lake to changes in these factors is studied using a simulation model of the lake ecosystem. Chl-a responses from both observed data and the simulated results are extracted by multiple regression. Results show that decreasing TP load decreases chl-a, but less at low TP levels (〈 10 mg TP · m−3). There is also a certain time period for peak river flow which gives the least yield of chl-a per unit TP. This time period occurs in early summer (i.e., around June 10) if the total phosphorus load is low, and later if the load is high. Both observations and simulation results show that a high water flow increases chl-a at low epilimnion depths (〈 15 m), but that the same high water flow decreases chl-a when epilmnion is deep.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877062
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  • 21
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    Nutrient-chlorophyll trajectories across trophic gradients (1992)
    Springer
    Aquatic sciences 54 (1992), S. 58-76 
    Details
    ISSN: 1420-9055
    Keywords: Eutrophication ; lake management ; phosphorus ; nitrogen ; chlorophyll-a ; slope estimator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We estimate the response of chl-a (mg · m−3) to changes in concentrations of total phosphorus (TP) by calculating the slopeS = Δchl-a/ΔTP in chl-a =f(TP) graphs. Results show that in years where algae are P-limited oligotrophic lakes respond less (median slope 0.21) to changes in nutrient concentrations than eutrophic lakes, (median slope 0.31) and these again less than hypereutrophic lakes, (median slope 1.02). We find no saturation value for the slope within the TP range considered (6–480 mg · m−3). Chl-a in eutrophic lakes responds more frequently to non-nutrient factors than oligotrophic and hypereutrophic lakes. Results obtained by replacing TP with a new nutrient parameter, TP′ = 0.056 · TP · IN0.226, in which inorganic nitrogen, IN, is factored in, suggest that nitrogen has an influence on chl-a in oligotrophic lakes. Blue-green algae respond less to changes in TP than other algal species, e.g., diatoms.
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    URL: http://dx.doi.org/10.1007/BF00877264
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    What controls levels of dissolved phosphate and ammonium in surface waters? (1993)
    Springer
    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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    URL: http://dx.doi.org/10.1007/BF00877441
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    The short term response to eutrophication abatement (1990)
    Springer
    Aquatic sciences 52 (1990), S. 199-220 
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    ISSN: 1420-9055
    Keywords: Eutrophication ; lake management ; phosphorus ; ecosystem ; chlorophyll-a ; mathematical modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compare results of a new model for predicting the short term inter annual changes in chlorophyll-a (chl-a) in lakes after reductions in total phosphorus (TP) to predictions made by least squares regression models. In the new method, slopes of chl-a/TP graphs (both axes in mg · m−3) are depicted in frequency diagrams and used to extract information on the expected, short term chl-a/TP response. The short term response for nine shallow (〈 10 m deep) and nutrient rich lakes to changes in TP was found to be: Chl-a = 0.49 · TP + 17.3, and for nine deep, P-limited lakes: Chl-a = 0.08 · TP + 3.5. If the TP-reduction is known to be greater than 10 mg · m−3, the expected slope increases to 0.58 for shallow lakes and to 0.26 for deep lakes. The slope, 0.58, is 8% lower than the slope for the long term response calculated by regression for the shallow lakes. For deep lakes the slope, 0.26, is 2 to 3 times higher than that calculated by regression, indicating that reductions in TP for deep lakes give greater effects than least squares regression equations suggest. We have also calculated the reduction in TP which will give about 80% probability that a reduction in chl-a will be observed next year. For shallow, P-limited lakes this reduction is about 30 mg · m−3 (5% of average initial in-lake TP concentration), and for deep lakes about 14 mg · m−3 (35% of average initial in-lake TP concentration).
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    URL: http://dx.doi.org/10.1007/BF00877280
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    Extraction inductively coupled plasma-optical emission spectrometry (ICP-OES) determination of traces of phosphorus in tungsten (1989)
    Springer
    Microchimica acta 99 (1989), S. 399-412 
    Details
    ISSN: 1436-5073
    Keywords: phosphorus ; tungsten ; preconcentration ; ICP-OES
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A method for the separation and preconcentration of traces of phosphorus from tungsten was developed. Solid phase extraction of the phosphovanadomolybdate complex performed on a micro-column was applied. Phosphorus was determined by optical emission spectroscopy (OES) with inductively coupled plasma (ICP) excitation. A limit of detection of 0.4 μg/g P with respect to the solid phase is obtained. By directly coupling the extraction/elution step to the ICP instrument a detection limit of 0.06 μg/g P in W was achieved. Besides, the complexity of spectral evaluation in ICP-OES determinations of traces in spectralline-rich matrices is discussed.
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    URL: http://dx.doi.org/10.1007/BF01244696
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    Surface acid property and its relation to SCR activity of phosphorus added to commercial V2O5(WO3)/TiO2 catalyst (1998)
    Springer
    Catalysis letters 53 (1998), S. 65-71 
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    ISSN: 1572-879X
    Keywords: selective catalytic reduction ; nitric oxide reduction ; phosphorus ; acid property
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract To examine the influence of phosphorus on the commercial V2O5(WO3)/TiO2 SCR catalyst, measurements were carried out by means of infrared and Raman spectroscopy, XPS, and NO reduction measurement as a function of phosphorus loading. Phosphorus added to the catalyst was found to disperse well over the catalyst without a significant agglomeration up to 5 wt% P2O5 addition. The number of the hydroxyl groups bonded to the vanadium and titanium species decreased readily with increasing amount of phosphorus. Correspondingly, the hydroxyl groups bonded to the phosphorus species were formed. NH3 adsorbed on both hydroxyl groups bonded to vanadium and phosphorus as ammonium ions, implying that the P–OH groups formed are also responsible for the Brønsted acidity. The NO reduction activity was found to be decreased with increasing amount of phosphorus; however, the influence of phosphorus was relatively small irrespective of the large amount of phosphorus addition. The deactivation might be caused by the change in the nature of the surface hydroxyl groups as Brønsted acid sites. Phosphorus species might partially wrap the surface V=O and W=O groups, which might also contribute to the deactivation.
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    Microstructural characterization and corrosion resistance of Ni–Zn–P alloys electrolessly deposited from a sulphate bath (1999)
    Springer
    Journal of applied electrochemistry 29 (1999), S. 637-645 
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    ISSN: 1572-8838
    Keywords: alloys ; electroless ; microstructure ; morphology ; nickel ; phosphorus ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electroless Ni–Zn–P alloy coatings were obtained on an iron substrate from a sulfate bath at various pH values. The effects of changes in bath pH on alloy composition, morphology, microstructure and corrosion resistance were studied. Scanning electron microscopy was performed to observe the morphological change of the deposits with bath pH. Coating crystallinity was investigated by grazing incidence asymmetric Bragg X-ray diffraction and transmission electron microscopy. A transition from an amorphous to polycrystalline structure was observed on increasing the bath alkalinity, and thus decreasing the phosphorus content of the alloys. A single crystalline phase corresponding to face-centred-cubic nickel was identified in the alloys obtained from a strong alkaline solution. An increase in zinc percentage up to 23% in the deposits does not change the f.c.c. nickel crystalline structure. Corrosion potential and polarization resistance measurements indicated that the corrosion resistance of electroless Ni–Zn–P alloys depends strongly on the microstructure and chemical composition. The deposits obtained at pH 9.0–9.5 and with 11.4–12.5% zinc and 11.8–11.2% phosphorous exhibited the best corrosion resistance.
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    URL: http://dx.doi.org/10.1023/A:1026441403282
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    Ni–Zn–P alloy deposition from sulfate bath: inhibitory effect of zinc (1999)
    Springer
    Journal of applied electrochemistry 29 (1999), S. 1171-1176 
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    ISSN: 1572-8838
    Keywords: alloys ; cyclic voltammetry ; electrodeposition ; electroless deposition ; nickel ; phosphorus ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electroless Ni–Zn–P alloy deposition from a sulphate bath, containing sodium hypophosphite as reducer, was investigated. To increase the plating rate, the deposition parameters were optimized. The effect of process parameters (T, pH and [Zn2+]) on the plating rate and deposit composition was examined and it was found that the presence of zinc in the bath has an inhibitory effect on the alloy deposition. As a consequence, the percentage of zinc in the electroless Ni–Zn–P alloys never reaches high values. Using cyclic voltammetry the electrodeposition mechanism of Ni–Zn–P alloys was investigated. It was observed that the zinc deposition inhibits the nickel discharge and, as a consequence, its catalytic activity on hypophosphite oxidation. It was also found that increase in temperature or pH leads to the deposition of nickel rich alloys.
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    URL: http://dx.doi.org/10.1023/A:1003426904395
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    Calibration of diatoms along a nutrient gradient in Florida Everglades Water Conservation Area-2A, USA (1999)
    Springer
    Journal of paleolimnology 22 (1999), S. 413-437 
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    ISSN: 1573-0417
    Keywords: diatoms ; Everglades ; phosphorus ; wetland ; calibration ; multivariate ; Florida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The relationship between diatom taxa preserved in surface soils and environmental variables at 31 sites in Water Conservation Area 2A (WCA-2A) of the Florida Everglades was explored using multivariate analyses. Surface soils were collected along a phosphorus (P) gradient and analyzed for diatoms, total P, % nitrogen (N), %carbon (C), calcium (Ca), and biogenic silica (BSi). Phosphorus varied from 315-1781 μg g-1, and was not found to be correlated with the other geochemical variables. Canonical correspondence analysis (CCA) was used to examine which environmental variables correlated most closely with the distributions in diatom taxa. Canonical correspondence analysis with forward selection, constrained and partial CCA, and Monte Carlo permutation tests of significance show the most significant changes in diatom assemblages along the P gradient (p 〈 0.01), with additional species differences correlated with soil C, N, Ca, and BSi. Weighted-averaging (WA) regression and calibration models of diatom assemblages to P and BSi were developed. The diatom-based inference model for soil [P] had a high apparent r2 (0.86) with RMSEboot = 218 μg g-1. Indicator diatom species identified by assessing species WA optima and WA tolerance to [P], such as Nitzschia amphibia and N. palea for high [P] (~1300-1400 μ g-1) and Achnanthes minutissima var. scotica and Mastogloia smithii for low [P] (~400-600 μg g-1), may be useful as monitoring tools for eutrophication in WCA-2A as well as other areas of the Everglades. Diatom assemblages analyzed by cluster analysis were related to location within WCA-2A, and dominant taxa within clusters are discussed in relation to the geochemical variables measured as well as hydrology and pH. Diversity of diatom assemblages and a ‘Disturbance Index’ based on diatom data are discussed in relation to the historically P-limited Everglades ecosystem. Diatom assemblages should be very useful for reconstructions of [P] through time in the Florida Everglades, provided diatoms are well preserved in soil cores.
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    URL: http://dx.doi.org/10.1023/A:1008049224045
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    Zinc and phosphorus interaction in a wheat-maize cropping system (1987)
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    Nutrient cycling in agroecosystems 13 (1987), S. 77-86 
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    ISSN: 1573-0867
    Keywords: zinc ; phosphorus ; interactions ; limed ; unlimed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To study the interaction effect of Zn and P in a wheat-maize cropping system, a field experiment was conducted at the H.P. Agricultural University Research Station, Palampur (India). Zinc was applied as ZnSO4·7H2O at the rate of 0, 20 and 40 kg per ha and P as superphosphate at the rate of 0, 60 and 120 kg per ha. The direct Zn-P interaction effect was investigated on wheat (S—308) and its residual effect on maize (early composite). Added Zn did not increase the grain and straw yield of wheat when P was not applied, but when P was applied, 20 kg per ha added Zn responded significantly. Contrary to this, in maize, only 20 kg per ha added Zn responded significantly when P was not applied, but when P was applied, even 40 kg per ha Zn increased the grain and straw yield of maize. The grain and straw yield of wheat and maize were higher under limed than under unlimed conditions. The concentration of Zn increased with the application of Zn and decreased with the application of P. The concentration of Zn was comparatively higher in grain than in straw of wheat and maize. The P concentration in wheat and maize plants decreased with the increasing levels of applied Zn. The concentrations of Zn were lower under limed than under unlimed condition, whereas the reverse was true for P concentrations. The respective absorption of Zn and P in wheat was 9.7 and 7.3 per cent upto tillering, 47.9 and 49.4 per cent between tillering and flowering, and 42.3 and 43.3 per cent between flowering and maturity. The corresponding absorption of Zn and P in maize was 11.7 and 9.4, 59.9 and 52.1, and 29.3 and 38.5 per cent before booting stage, between booting and tasseling stage and between tasseling and maturity stage, respectively. At maturity, about 53.1 and 13.0 per cent of the Zn and P taken up were retained by wheat straw and 46.9 and 87.0 per cent by wheat grain. The respective values for Zn and P in maize straw and grain were 66.8 and 30.3 and 33.2 and 69.7 per cent. When more Zn was applied, less Zn was translocated to grains; when more P was added, more Zn was translocated to grains. The effects of P and Zn on P distribution at maturity were opposite to that of Zn distribution.
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    The variation of element contents in triticale during vegetative growth (1987)
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    Nutrient cycling in agroecosystems 13 (1987), S. 155-159 
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    ISSN: 1573-0867
    Keywords: triticale ; contents of nitrogen ; phosphorus ; potassium ; calcium ; magnesium ; trace elements ; heavy metals ; stage of growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Zusammenfassung Es wurden die Schwankungen in den Konzentration von N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, B, Ba, Be, Bi, Sn, Sr, Sb, Ti, Te, V, Se, As und Hg in Triticale unter Feldbedingungen untersucht. Von der Bestockung bis zur Vollreife wurden alle 10 Tage von je 0.5 m2 pro Parzelle Pflanzenproben genommen. In allgemeinen haben die Konzentrationen von Frühjar bis zur Ernte abgenommen. Der elementengehalt in Triticale war demjenigen der übrigen Getreidearten verschieden, aber der Trend der Änderungen war ähnlich.
    Notes: Abstract The variation of N, P, K, Ca, Mg, Fe, Mn, Zn, Cu, B, Ba, Be, Bi, Sn, Sr, Sb, Ti, Te, V, Se, As and Hg concentrations was studied under field conditions in triticale. The samples were collected every 10 days from tillering to full ripening stage using plant material from 0.5 m2 per plot. The concentrations generally decreased from early growth to harvest. The elemental concentrations in triticale differed from the other cereals, but the variation's trend was similar.
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    Fertilizer requirement of rice-wheat and maize-wheat rotations on coarse-textured soils amended with farmyard manure (1988)
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    Nutrient cycling in agroecosystems 17 (1988), S. 153-164 
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    ISSN: 1573-0867
    Keywords: farmyard manure ; maize ; nitrogen ; phosphorus ; rice ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field experiments with rice-wheat rotation were conducted during five consecutive years on a coarse-textured low organic matter soil. By amending the soil with 12t FYM ha−1, the yield of wetland rice in the absence of fertilizers was increased by 32 per cent. Application of 80 kg N ha−1 as urea could increase the grain yield of rice equivalent to 120 kg N ha−1 on the unamended soil. Although the soil under test was low in Olsen's P, rice did not respond to the application of phosphorus on both amended and unamended soils. For producing equivalent grain yield, fertilizer requirement of maize grown on soils amended with 6 and 12 t FYM ha−1 could be reduced, respectively to 50 and 25 per cent of the dose recommended for unamended soil (120 kg N + 26.2 kg P + 25 kg K ha−1). Grain yield of wheat grown after rice on soils amended with FYM was significantly higher than that obtained on unamended soil. In contrast, grain yield of wheat which followed maize did not differ significantly on amended or unamended soils.
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    Brown leaf spot disease and fertilizer interaction in irrigated rice growing on different soil types (1995)
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    Nutrient cycling in agroecosystems 42 (1995), S. 117-121 
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    ISSN: 1573-0867
    Keywords: Cochliobolus miyabeanus ; rice brown leaf spot ; phosphorus ; disease-fertilizer interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Studies have been undertaken in a 1000 ha area of irrigated rice (Oryzica sativa) at Caroni (1975) Limited to determine the effect of the fertilizer programme on the incidence of important diseases. Over a period of three years higher levels of brown leaf spot (Cochliobolus miyabeanus) on rice varieties Oryzica 1 and Oryzica 5 on three different soil types were associated with increasing levels of leaf P, from a low of 0.149% of dry matter (DM) to a high of 0.396% DM. On the Washington silty clay loam series (Inceptisol) brown leaf spot incidence was lowest when leaf P was between 0.135% and 0.149% of DM. However, disease incidence was higher when leaf P levels fell to 0.133% of DM or rose above 0.149%, under conditions where N was more than adequate. The moderate levels of the disease experienced over the period had no effect on yield, as grain infection was minimal. The results support the conclusion that the incidence of brown leaf spot on irrigated rice at Caroni is influenced by sub-optimal levels paticularly of P. Careful monitoring and managememt of P nutrition is seen as an important part in the overall strategy for controlling the disease.
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    Effect of phosphate on the sorption, desorption and plant-availability of selenium in soil (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 189-197 
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    ISSN: 1573-0867
    Keywords: interaction ; isotopic exchange ; phosphorus ; plant-availability ; selenium ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphate, applied at 5µg P cm−3, decreased selenite sorption by from 30–70% in three soils studied. Both maximum sorption (Xm) and the binding-energy of sorption as indicated by the binding-energy related constant (k) or the molar free energy (ΔG) of the sorption reaction derived from the Langmuir equation were considerably decreased. On the other hand, phosphate sorption was decreased by increasing concentration of selenite from 0.2µg Se cm−3 to 1.0µg Se cm−3 in the initial solution. The competitive sorption of phosphate with selenite was likely the main mechanism involved in the P-Se interactions. The competitively sorbed selenite exhibited much larger desorption in 0.01M CaCl2 solution, more readily extractable to 0.5M NaHCO3 and significantly higher isotopic exchangeability compared to that sorbed without the competing anion. Results from pot trial using ryegrass indicated that phosphate application increased more efficiently the plant-availability of applied fertilizer Se than that of indegeneous Se in soil.
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    The potential use of wetlands to reduce phosphorus export from agricultural catchments (1993)
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    Nutrient cycling in agroecosystems 36 (1993), S. 157-164 
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    ISSN: 1573-0867
    Keywords: phosphorus ; wetlands ; nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Natural and artificial wetlands have the potential to reduce phosphorus (P) loads from dispersed agricultural runoff and from point sources in the Peel-Harvey catchment, Western Australia. Small experimental systems containing wetland plants and substrate have shown significant removal of P from inflowing water, the proportion of P removed being dependent on P concentration and flow rate of water through the system. The use of artificial wetlands to treat diffuse agricultural runoff is limited by the highly seasonal runoff typical of this Mediterranean climate, while use at point sources has so far been unsuccessful because compounds from the effluent clog the wetland ‘filters’. Treatment at point sources may well be feasible after further research. Natural wetlands in the catchment absorb P received in runoff from farmland and, in the absence of any outflow channels to the drainage system, confine this P within the boundaries of the wetland. Disturbance to wetlands may reduce their efficiency in absorbing nutrients and may release P stored in the vegetation and sediment to the water. The conservation of natural wetlands is recommended to maximise nutrient retention in the catchment.
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    An expanded weighted-averaging model for inferring past total phosphorus concentrations from diatom assemblages in eutrophic British Columbia (Canada) lakes (1995)
    Springer
    Journal of paleolimnology 14 (1995), S. 49-67 
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    ISSN: 1573-0417
    Keywords: diatoms ; eutrophication ; lake management ; paleolimnology ; British Columbia ; lakes ; phosphorus ; training sets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Eighteen lakes were added to a published training set of 46 British Columbia (BC) lakes in order to expand the original range of total phosphorus (TP) concentrations. Canonical correspondence analysis (CCA) was used to analyze the relationship between diatom assemblages and environmental variables. Specific conductivity and [TP] each explained significant (P≤0.05) directions of variance in the distribution of the diatoms. The relationship between diatom assemblages and [TP] was sufficiently strong to warrant the development of a weighted-averaging (WA) regression and calibration model that can be used to infer past trophic status from fossil diatom assemblages. The relationship between observed and inferred [TP] was not improved by the addition of more eutrophic lakes, however the [TP] range and the number of taxa used in the transfer function are now superior to the original model. Diatom species assemblages changed very little in lakes with TP concentrations greater than 85 µg 1−1, so we document the development of a model containing lakes with TP≤85 µg 1−1. The updated model uses 59 training lakes and covers a range of species optima from 6 to 41.9 µg 1−1 TP, and a total of 150 diatom taxa. The updated inference model provided a more realistic reconstruction of the anthropogenic history of a highly eutrophic BC lake. The model can now be used to infer past nutrient conditions in other BC lakes in order to assess changes in trophic status.
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    Stable isotope (δ13C and δ15N) signatures of sedimented organic matter as indicators of historic lake trophic state (1999)
    Springer
    Journal of paleolimnology 22 (1999), S. 205-221 
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    ISSN: 1573-0417
    Keywords: carbon isotopes ; diatoms ; lake management ; nitrogen isotopes ; phosphorus ; radium-226 ; sediments ; trophic state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We explored the use of carbon and nitrogen isotopes (δ13C and δ15N) in sedimented organic matter (OM) as proxy indicators of trophic state change in Florida lakes. Stable isotope data from four 210Pb-dated sediment cores were compared stratigraphically with established proxies for historical trophic state (diatom-inferred limnetic total phosphorus, sediment C/N ratio) and indicators of cultural disturbance (sediment total P and 226Ra activity). Diatom-based limnetic total P inferences indicate a transition from oligo-mesotrophy to meso-eutrophy in Clear Lake, and from eutrophy to hypereutrophy in Lakes Parker, Hollingsworth and Griffin. In cores from all four lakes, the carbon isotopic signature of accumulated OM generally tracks trophic state inferences and cultural impact assessments based on other variables. Oldest sediments in the records yield lower diatom-inferred total limnetic P concentrations and display relatively low δ13C values. In the Clear, Hollingsworth and Parker records, diatom-inferred nutrient concentrations increase after ca. AD 1900, and are associated stratigraphically with higher δ13C values in sediment OM. In the Lake Griffin core, both proxies display slight increases before ~1900, but highest values occur over the last ~100 years. As Lakes Clear, Hollingsworth and Parker became increasingly nutrient-enriched over the past century, the δ15N of sedimented organic matter decreased. This reflects, in part, the increasing relative contribution of nitrogen-fixing cyanobacteria to sedimented organic matter as primary productivity increased in these waterbodies. The Lake Griffin core displays a narrow range of both δ13C and δ15N values. Despite the complexity of carbon and nitrogen cycles in lakes, stratigraphic agreement between diatom-inferred changes in limnetic total P and the stable isotope signatures of sedimented OM suggests that δ13C and δ15N reflect shifts in historic lake trophic state.
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    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 
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    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.
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    Ability of a dynamic model of phosphorus to account for observed patterns of response in a series of phosphate fertilizer trials on pasture (1995)
    Springer
    Nutrient cycling in agroecosystems 40 (1995), S. 21-29 
    Details
    ISSN: 1573-0867
    Keywords: model ; pasture ; phosphorus ; RPR ; reactive phosphate rock ; Sechura phosphate rock ; SPR ; superphosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A national series of rates × forms of phosphate fertilizer trials has provided a large amount of data on patterns of response of pasture production and soil P tests to forms, rates and frequencies of P fertilizer application over time. A simple mechanistic model of P in pastoral systems has been developed in an attempt to account for the observed patterns. The model considers active P in the soil to be in one of two compartments: undissolved fertilizer P (PF) and a pool of labile, plant-available P (PA). P dissolving from PF enters PA, and P is lost from PA by immobilisation in the soil and by net removal above ground through non-recycled uptake by plants. Both these transfers are taken to follow first order kinetics, with rate constants designated K1 and K2 respectively. Pasture dry matter (DM) production in any year is related to the mid-year value of PA by the diminishing-returns Mitscherlich equation, with nil pasture yield being associated with nil PA. Data from different sites with the same design were combined to give generalised response patterns with which to assess the model. Only the control treatment and treatments receiving triple superphosphate (TSP) and Sechura phosphate rock (SPR) were considered. With a value for K1 corresponding to almost immediate dissolution, the model accounted well for the Olsen soil P test patterns from TSP when K2 corresponded to an annual loss of 16.3% of P in PA and a factor of 10 was used to convert Olsen P to kg P/ha in PA. Pasture DM yield response curves to rates of TSP in individual years were well accounted for when the mid-year value of PA required for 90% relative yield was taken as 130 kg P/ha. The model also accounted well for the difference between response patterns to annual and triennial TSP applications for both soil P tests and DM production. The declines in soil P tests and DM production which occurred in nil P controls were less than model predictions: this could be due to unfertilised pasture making more use of P from greater soil depth or less available forms. Olsen P tests with the higher rates of SPR were always lower than model predictions using a value for K1 derived from chemical measurement of SPR dissolution rates in the trials. However, DM yields from SPR were generally close to model predictions. These divergent results support independent data suggesting that available soil P from reactive phosphate rocks (RPRs) is underestimated by the Olsen P test. The relative success of this simple compartmental model in accounting for generalised response patterns in such a large body of data suggests that it could be a useful starting point for a dynamic P fertilizer recommendation model.
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    URL: http://dx.doi.org/10.1007/BF00749859
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    Fertility characterization of soils at six research sites in NW Cameroon (1995)
    Springer
    Nutrient cycling in agroecosystems 41 (1995), S. 49-57 
    Details
    ISSN: 1573-0867
    Keywords: Cameroon ; fertility ; phosphorus ; site characterization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fertility capability of surface (0–20 cm) soils was evaluated at six sites in the North-West Cameroon highlands. Two main soil groups, designated as Classes A and B, were identified based on elevation. The Class A soils from low elevations (600–1178 m) had higher Ca, Mg, K, pH, sorbed less P and were lower in organic carbon and sesquioxides than the highland (〉 1200 m) soils. Soil acidity (Al saturation 〉 30%) and high P sorption appeared to be the most limiting factors to crop production especially on the Class B soils where the Standard P Requirement exceeded 500 mg kg−1. Phosphorus sorption data were best described by the Freundlich equation. Amorphous aluminium was the most important determinant of solution P concentration (r = 0.85,p 〈 0.001) followed by soil organic carbon, (r = 0.80,p 〈 0.001) at high P rates. Nitrogen deficiency symptoms of maize were pronounced on the Class B soils. Consequently, crop growth and yield were lower on Class B than on Class A soils despite the high organic carbon in B. We hypothesize that the supply of high quality organic material (high in N and low in lignin and polyphenols) at site B through agroforestry and related cropping systems, would improve the fertility of the soil and crop yield.
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    URL: http://dx.doi.org/10.1007/BF00749520
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    Future directions for agricultural phosphorus research (1995)
    Springer
    Nutrient cycling in agroecosystems 41 (1995), S. 167-178 
    Details
    ISSN: 1573-0867
    Keywords: phosphorus ; workshop ; environment ; review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A workshop was held in 1990 in Muscle Shoals, Alabama to discuss current and future research on phosphorus in agriculture. Twenty four presentations were given in areas ranging from basic to applied research. For five of the research areas presented at the workshop, this paper presents a literature review, a review of presentations at the workshop, and a discussion of future research ideas.
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    URL: http://dx.doi.org/10.1007/BF00748306
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    Long term effects of inorganic fertilizer inputs on crop productivity in a rice-wheat cropping system (1998)
    Springer
    Nutrient cycling in agroecosystems 51 (1998), S. 193-200 
    Details
    ISSN: 1573-0867
    Keywords: cropping systems ; inorganic fertilizer ; nitrogen ; organic carbon ; phosphorus ; potassium ; rice-wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three levels of N (40,80,120 kg N ha-1) and P (0,17.5,35 kg P ha-1), and 2 levels of K (0,33 kg K ha-1) were tested for 19 years in rice and wheat crops of a rice-wheat cropping system in a fixed layout of 3×2×2 factorial partially confounded design along with one control and 3 replications. From this trial, data of 7 treatments, i.e. 0-0-0, 40-35-33, 80-35-33, 120-35-33, 120-0-0, 120-35-0 and 120-0-33 kg ha-1 N-P-K respectively were compared for yield trends, changes in response functions, soil organic -C and available N,P,K status. Soil organic - C decreased in unfertilized plots by 62% (over initial value of 0.45%) but increased by 44, 40 and 36% in plots receiving 120-35-33, 120-35-0 and 80-35-33 kg ha-1 N-P-K respectively. Available N was also greatest in these same three treatments. Available soil P increased by about 5 fold in 15 years in treatments supplied with fertilizer P, but no significant change was detected in treatments without P addition. Yields of rice and wheat exhibited linear declining trend in all treatments. The highest rate of decline (89 kg ha-1 year-1 in rice and 175 kg ha-1 year-1 in wheat), however, was found when 120 kg ha-1 N was applied alone. The least rate of decline of 20 kg ha-1 year-1 in rice and 58 kg ha-1 year-1 in wheat was observed when 40-35-33 kg ha-1 N-P-K respectively was applied to both the crops. At currently recommended levels of NPK (120-35-33 kg ha-1), the rate of decline in yields was 25 kg ha-1 year-1 for rice and 62 kg ha-1 year-1 for wheat. Possible causes of these yield declines are discussed.
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    URL: http://dx.doi.org/10.1023/A:1009744719420
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    The mycorrhizal fungus Glomus mosseae enhances growth, yield and chemical composition of a durum wheat variety in 10 different soils (1998)
    Springer
    Nutrient cycling in agroecosystems 52 (1998), S. 1-7 
    Details
    ISSN: 1573-0867
    Keywords: durum wheat ; Glomus mosseae ; micronutrients ; nutrient uptake ; phosphorus ; vesicular-arbuscular ; mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of the vesicular arbuscularmycorrhizal fungus (VAMF) Glomus mosseae ongrowth, yield and nutrients' uptake of the durum wheatvariety ‘Sifnos’ was investigated in ten differentsoils. Inoculation had a positive effect on tillering,improved plant growth up to 11.6 times and increasedgrain yield up to 5.4 times as compared tonon-inoculated plants. The thousand kernels weight wasimproved by up to 60%. The analysis of shoot tissue ofthe mycorrhizal plants showed that P concentration wasincreased up to 4 fold, while the K, Ca and Mg uptakewas similar for both mycorrhizal and non-mycorrhizalplants. The concentrations of the trace elements Mn,Zn, Fe and Cu were lower in the mycorrhizal plantscompared to that of non-inoculated ones. The P and Mgconcentration of the grains produced by the inoculatedplants was increased while the Ca concentration wasdecreased. The concentration of the heavy metals waseither decreased ( Mn, Fe, Co, Cr, Ni, Pb) or remainedunchanged (Zn, Cu). The colonization in the roots ranged from 23 to 78%.
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    URL: http://dx.doi.org/10.1023/A:1016311118034
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    Changes in fertilizer and manurial practices during 1960–1990: implications for N and P inputs to the Ythan catchment, N.E. Scotland (1998)
    Springer
    Nutrient cycling in agroecosystems 52 (1998), S. 19-29 
    Details
    ISSN: 1573-0867
    Keywords: agriculture ; catchment ; fertilizer ; historical ; manure ; nitrate ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A suggested increase in the growth of macrophytic algae within the Ythan estuary (N.E. Scotland) over recent years has been linked to the increased amounts of nitrogen in the form of NO3–N entering the estuary from the river. The increased NO3 concentration in the river has been associated with recent changes in farming practices in this predominantly agricultural catchment. Terrestrially derived phosphorus is also considered to contribute increasingly to eutrophication of fresh waters. Historical agricultural census data together with appropriate surveys of fertilizer practice were used to calculate the total quantities of fertilizer and manure derived N and P applied annually over the wholeYthan catchment during the period 1960 – 1990. While the total agricultural land area has remained similar, significant changes in cropping practice have occurred. In particular, a greater proportion of land is given to autumn sown crops while the area of grassland has declined. These changes in farming practice are associated with differences in both the total amounts and timing of fertilizer applied. The use of inorganic N in the catchment has trebled since 1960 and is currently approximately 6400 tonnes (104 kg N/ha). The use of P has decreased by more than a quarter to 1274 tonnes (21 kg P/ha) over a similar time period. There has been no obvious change in total quantity of N and P derived from animal manures, estimated to be 44 and 11 kg per ha, respectively, when averaged over the area of agricultural land. Cattle and sheep numbers have remained relatively constant and together account for approximately 80% of the manure N and 70% of the manure P produced annually. However, poultry have declined by 70% since 1960 while pig numbers have increased six-fold. The average annual application rate of manure derived N over the whole catchment (44 kg/ha) is considerably below that proposed at the farm scale in the EC Nitrate Directive (210–170 kg/ha). However, on a local scale difficulties may arise for large manure producing concerns such as dairy or pig units.
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    URL: http://dx.doi.org/10.1023/A:1009787618943
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    Applications of poultry litter and triple superphosphate fertilizer to a sandy soil: effects on soil phosphorus status and profile distribution (1999)
    Springer
    Nutrient cycling in agroecosystems 54 (1999), S. 233-242 
    Details
    ISSN: 1573-0867
    Keywords: leaching ; phosphorus ; poultry litter ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To determine P loadings, added through poultry litter, sufficient to cause downward movement of P from the cultivated layer of a sandy soil, six rates of poultry litter were applied annually for four years to a site in central England. (total loading 0 – 1119 kg P ha-1). A single extra plot also received an extra 1000 kg ha-1 as triple superphosphate (TSP; total loading 2119 kg P ha-1) and three other treatments received 200 – 800 kg ha-1 P as TSP only. Annual soil sampling in 30-cm increments to 1.5-m depth provided information on P build-up in the topsoil and P movement to depth. There were strong linear trends between P balance (P applied – P removed in crops) and total P, Olsen bicarbonate extractable P and water-soluble P in the topsoil. Phosphorus from TSP and poultry litter fell on the same regression lines, suggesting that both would be equally effective as fertilizer sources. We calculated that 100 kg ha-1 surplus total P would increase the Olsen extractable P content by c. 6 mg kg-1 and the water-soluble P by c. 5 mg kg-1. Thus, relatively large amounts of P would need to be applied to raise soil P status. We found some evidence of P movement into the soil layers immediately below cultivation depth. However, neither soil sampling nor soil solution extracted through Teflon water samplers showed evidence of movement into the deep subsoil (1 m) despite large P loadings.
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    Inorganic phosphorus and manure effects on bahiagrass production on a Spodosol (1999)
    Springer
    Nutrient cycling in agroecosystems 54 (1999), S. 259-266 
    Details
    ISSN: 1573-0867
    Keywords: bahiagrass ; manure ; pasture fertilization ; phosphorus ; phosphorus cycling ; Spodosol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bahiagrass (Paspalum notatum Flugge) pasture fertilization recommendations have traditionally been based upon clipping studies. Inclusion of P from manure, not originally considered when P recommendations were developed for pastures, may minimize the need for P fertilization without reducing bahiagrass production or P uptake. The objective of this research was to determine if manure contributes greatly to the P crop nutrient requirement. A 2-year field study utilized a factorial arrangement of 0 and 6.9 Mg air-dried manure ha-1 with 0, 17, 34, 51, and 68 kg inorganic P ha-1 from triple superphosphate to evaluate bahiagrass yield, root distribution, and P uptake response on a Myakka fine sand (sandy, siliceous, hyperthermic Aeric Alaquod). Because air-dried manure was used in the field study, a greenhouse study was employed to confirm that there were no differences in bahiagrass yield or P uptake from either air-dried or fresh cattle (Bos spp.) manure sources. There were no manure or manure by P interaction effects on yield or P uptake of bahiagrass indicating that manure source did not effect grass production in the greenhouse. In the field study, bahiagrass roots were distributed into the Bh horizon, and the Bh horizon had at least four times more Mehlich-1 extractable P than that of the Ap horizon. This horizon was most likely acting as a main source for P-uptake by the grass. This observation was further confirmed by no yield response to levels of inorganic P application in 1989. A linear-response-and-plateau (R2=0.196) relationship with a critical point of 15.4 kg P ha-1 was found in 1990. Bahiagrass yield and P uptake were not dependent on P fertilization, either from manure or inorganic P, due to the availability of P from the Bh horizon.
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    Controlling soil water content in fertiliser dissolution experiments (1999)
    Springer
    Nutrient cycling in agroecosystems 55 (1999), S. 7-14 
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    ISSN: 1573-0867
    Keywords: fertiliser formulation ; nutrients ; phosphorus ; relative humidity ; soil moisture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus lost in runoff from agricultural land leads to the enrichment of surface waters and contributes to algal blooms. Fertilisers are one source of this P. To compare the water available P of different fertiliser formulations in the laboratory it is necessary to control environmental conditions, temperature, relative humidity and soil water content, prior to simulating rainfall. Two chambers were designed in which relative humidity and soil water content were controlled using salt solutions. An initial design comprising a sealed chamber with three layers of soil samples over a salt bath was found to be inferior to a single layer design. The changes in water content of soil samples were used to test the single layer chamber in a constant temperature environment (15 °C) using a saturated KCl solution (90% relative humidity). Based on the final soil water content of the samples, the spatial variation within the chamber was within tolerable limits. The single layer chamber was used for a simulation experiment comparing the water available P of two commercial fertilisers. Using a saturated resorcinol solution (95% relative humidity) soil samples were equilibrated at 15 °C for 21 days, fertiliser added, and the water available P measured up to 600 h after fertiliser application. The results indicate that the amount of water available P was related to the fertiliser compound and exponentially related to the time since fertiliser application. It was concluded that the single layer chamber is suitable for controlling relative humidity and soil water content in trials such as these where the water available P of fertilisers are being compared.
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    URL: http://dx.doi.org/10.1023/A:1009816716466
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    Transfers of phosphorus within three dairy farming systems receiving varying inputs in feeds and fertilizers (1999)
    Springer
    Nutrient cycling in agroecosystems 55 (1999), S. 63-75 
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    ISSN: 1573-0867
    Keywords: dairy systems ; feeds ; fertilizers ; phosphorus ; P surplus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inputs of phosphorus (P) above requirements for production on dairy farms lead to surplus P with increased risk of P transfer in land run-off to surface waters causing eutrophication. The impact of reducing surplus P inputs in purchased feeds and fertilizers on milk and forage production was investigated in a comparison of three dairy farm systems on chalkland soils in southern England over a 3-year period. In accordance with current commercial practice, no attempt was made to regulate P inputs in system 1, which accumulated an average annual surplus of 23 kg P ha-1. Progressive reductions in purchased feed and/or fertilizer inputs into systems 2 and 3 decreased surplus P to 17 and 3 kg ha-1, respectively, without apparently limiting either milk or herbage dry matter production. The estimated reduction in faecal P output from system 3 cows fed a low P diet compared to system 1 cows fed a high P diet was 26%. Milk P concentrations significantly (P 〈0.001) increased in systems 2 and 3 which included maize in the diet. Output of P in milk and meat products, as a proportion of the total dietary P inputs, increased from 28% in system 1 to 36% in system 3. Surplus P was greatest in continuous maize fields receiving both dairy manure and starter P fertilizer. Withholding P fertilizer in system 3 did not reduce P offtake in cut herbage on soils of moderate P fertility. Total annual losses of P in storm run-off and leaching were no greater than annual inputs of P from the atmosphere (0.5 kg ha-1). The results indicate there is scope to reduce surplus P on commercial dairy farms without sacrificing production targets at least in the short term. Purchased feeds are the largest of the P inputs on intensive dairy farms, yet these are rarely quantified on commercial holdings.
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    URL: http://dx.doi.org/10.1023/A:1009860915462
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    Phosphorus (P) management in the ‘De Marke’ dairy farming system (2000)
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    Nutrient cycling in agroecosystems 56 (2000), S. 219-229 
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    ISSN: 1573-0867
    Keywords: phosphorus ; P ; dairy farming ; systems research ; environment ; pollution ; soil fertility ; sandy soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the sandy regions of the Netherlands water quality is threatened by high losses of nutrients from intensive dairy farms. About 67% (32 kg ha-1yr-1) of farm inputs of P in purchased feeds and fertilisers do not leave in milk or cattle. The Dutch government defined decreasing maximum permitted nutrient surplusses for the period 1998–2008, at 9 kg ha-1yr-1 for P. Farmers suppose that reducing the surplusses will be costly, because it limits application of slurry, which then has to be either exported or additional land has to be purchased. Moreover, farmers are worried about the impact on soil fertility and crop growth. To explore the possibilities of reducing surplusses by improved management, farming systems research is carried out at prototype farm ‘De Marke’. Results indicate that average intensive dairy farms can reduce P surplus sufficiently, without the need to buy land or to export slurry. Key factors are reductions in purchased feeds (by reduced needs per kg milk as a result of a higher milk yield per cow, less young stock and judicious feeding) and fertilisers (by improved management of ‘home-made’ manure and an increased maize area). Initially, P fertility status of the fields of ‘De Marke’ decreased, but stabilised in the seventh year at a level not restrictive to crop production.
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    A conceptual model for initial and residual responses to phosphorus fertilizers (1985)
    Springer
    Nutrient cycling in agroecosystems 6 (1985), S. 131-138 
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    ISSN: 1573-0867
    Keywords: modelling ; phosphorus ; residual value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A model is formulated to describe the amount of effective phosphorus in soil. For a source that is immediately fully effective only three parameters are required — the amount of effective phosphorus initially present, the proportion of phosphorus remaining effective after each year, and a parameter which determines the lower limit for the amount of effective phosphorus. An extension of the model to sources that release their phosphorus slowly requires one further parameter — the fraction of such phosphorus released each year. The effective phosphorus in soil is then related to yield using the Mitscherlich equation. The model gave a good description of the growth response ofStylosanthes humilis to superphosphate and calcined Christmas Island C-grade phosphate (CCICP) over three years on a red earth at Katherine, N.T. Furthermore, it enabled a quantitative assessment to be made of the residual value of the CCICP that was not achieved in an earlier analysis of the data.
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    Effect of P fertilizer on alleviating chloride toxicity in wheat (1985)
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    Nutrient cycling in agroecosystems 6 (1985), S. 171-176 
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    ISSN: 1573-0867
    Keywords: Chloride ; phosphorus ; salinity ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A pot study with four levels each P (control, 6.5, 13.0, 19.5 mg kg−1) and Cl− in irrigation water (control, 30, 60, 90me l−1) was carried out to test Cl− and P interaction on wheat. It has been found that optimum P nutrition alleviates the toxic effect of excess Cl−. Highest P rate resulted in a significant yield increase upto a Cl− level of 60me l−1. Cl− depressed P content in the plant only at a Cl− level of 90me l−1, while P rates had no major impact on the Cl− concentration in the plant. Lower Cl− concentration at higher P rates are rather a dilution effect than an antagonistic one. With optimum P supply higher Cl− contents in the plants were tolerated than with a low P supply.
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    Tracking phosphorus patterns in mango (Mangifera indica L) and possible relations to floral induction (1985)
    Springer
    Nutrient cycling in agroecosystems 6 (1985), S. 225-234 
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    ISSN: 1573-0867
    Keywords: bark ; floral induction ; leaves ; mango ; phosphorus ; shoots ; stems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphorus concentration was tracked in four types of mango shoots. The mean phosphorus concentration was highest in laterals existing on shoots which had either flowered or fruited in the preceding season, followed by young flush arising in July, laterals existing on shoots which did not flower or fruit in the preceding season and shoots which did not flower or fruit in the preceding season and having further extension of growth. A higher percentage of floral induction was noted in the laterals on shoots which had either flowered or fruited in the preceding season. The study clearly showed the association of availability of phosphorus with floral induction.
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    Response of two okra (Abelmoschus esculentus L. Moench) varieties to fertilizers: Yield and yield components as influenced by nitrogen and phosphorus application (1985)
    Springer
    Nutrient cycling in agroecosystems 6 (1985), S. 257-267 
    Details
    ISSN: 1573-0867
    Keywords: nitrogen ; okra (Abelmoschus esculentus L. Moench) ; phosphorus ; yield ; yield components
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The response of two okra (Abelmoschus esculentus L. Moench) varieties (‘White velvet’ and ‘NHAE 47-4’) to fertilization in northern Nigeria was examined using four rates of nitrogen (0, 25, 50 and 100 kg ha−1) and three rates of phosphorus (0, 13 and 26 kg ha−1). Nitrogen application significantly increased green pod yield, pod diameter, number of fruits per plant, number of seeds per pod and pod weight. Application of phosphorus also significantly increased green pod yield, pod number and number of seeds per pod. The two varieties responded to nitrogen application differentially with respect to green pod yield. For optimum green pod yield of ‘White velvet’ 35 kg N ha−1 is suggested while for variety ‘NHAE 47-4’, N fertilization can be increased to 70 kg ha−1. There was no differential response of varieties to phosphorus fertilization for green pod yield; however, the application of 13 kg ha−1 enhanced the performance of both varieties.
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    Effects of temperature on nutrient release from slow-release fertilizers (1996)
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 179-187 
    Details
    ISSN: 1573-0867
    Keywords: electrical conductivity ; leaching ; nitrogen ; pH ; phosphorus ; potassium ; release pattern ; slow-release fertilizers ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the effect of temperature on the release of N, P, and K from slow-release fertilizers (SRF). The study was conducted in micro-lysimeters filled with moist peat medium. Increasing the temperature from 4 to 12°C slightly increased N release from three different slow-release N (SRN) carriers with different particle sizes and coating thicknesses. At 21°C the rate of release was significantly different than the other two temperatures. Urea formaldehyde (UF), sulphur coated urea (SCU) and coated calcium nitrate (CCN), incubated in sphagnum moss peat, released between 3 and 20% of the applied N in six weeks. For eight synthetic and organic NPK carriers, the release pattern was similar to UF and SCU. However, the leaching losses of N from the NPK fertilizers were up to twenty times more than for the SRN products. Except for Osmocote® and Duna, which released 30–40% of the applied N as mineral-N within six weeks, all other slow-release and slowly mineralized NPK carriers acted like readily water-soluble compound NPK. Temperature did not affect the nutrient release from NPK fertilizers.
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    A nitrogen and phosphorus herbage nutrient index as a tool for assessing the effect of N and P supply on the dry matter yield of permanent pastures (1996)
    Springer
    Nutrient cycling in agroecosystems 47 (1996), S. 59-69 
    Details
    ISSN: 1573-0867
    Keywords: fertilizer ; nitrogen ; nutrition ; pastures ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to propose consistent decision rules for fertilizer supply, a study was made on the effect of additions of N and P fertilizers and of their interaction on the above-ground dry matter yield of pastures during spring. The interaction between N and P could occur through nutrient acquisition or nutrient efficiency for growth. We therefore characterised the herbage N and P status (N and P index) from previously established critical curves of herbage mineral content according to above-ground dry matter. First we studied the effect of N and P addition on herbage nutrient status. Secondly, we expressed the above-ground dry matter as a function of the herbage nutrient status. This study consisted of four treatments applied to four permanent pastures which had a low phosphorus availability. The results showed a positive effect of P supply on the herbage nitrogen status, which may be due to an increase of organic matter mineralization or root growth. The P herbage status decreased only if N was supplied without P. The dry matter yield was positively related to the herbage nitrogen status, but a low P herbage status reduced the slope of the relationship. For the pastures studied, the indirect effect of P supply on above-ground dry matter, revealed by an increase in N index, was greater than its direct effect. This methodology allows us to distinguish the direct and indirect effects of N and P addition on herbage growth at field level. It could be used to propose consistent rules to manage jointly both N and P supplies.
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    URL: http://dx.doi.org/10.1007/BF01985719
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    The value of poultry manure for wetland rice grown in rotation with wheat (1996)
    Springer
    Nutrient cycling in agroecosystems 47 (1996), S. 243-250 
    Details
    ISSN: 1573-0867
    Keywords: fertilizer value ; nitrogen ; phosphorus ; poultry manure ; urea ; wetland rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Poultry manure applied alone or in combination with urea at different N levels was evaluated as a N source for wetland rice grown in a Fatehpur loamy sand soil. Residual effects were studied on wheat which followed rice every year during the three cropping cycles. In the first year, poultry manure did not perform better than urea but by the third year, when applied in quantities sufficient to supply 120 and 180 kg N ha−1, it produced significantly more rice grain yield than the same rates of N as urea. Poultry manure sustained the grain yield of rice during the three years while the yield decreased with urea. Apparent N recovery by rice decreased from 45 to 28% during 1987 to 1989 in the case of urea, but it remained almost the same (35, 33 and 37%) for poultry manure. Thus, urea N values of poultry manure calculated from yield or N uptake data following two different approaches averaged 80, 112 and 127% in 1987, 1988 and 1989, respectively. Poultry manure and urea applied in 1:1 ratio on N basis produced yields in between the yields from the two sources applied alone. After three cycles of rice-wheat rotation, the organic matter in the soil increased with the amount of manure applied to a plot. Olsen available P increased in soils amended with poultry manure. A residual effect of poultry manure applied to rice to supply 120 or 180 kg N ha−1 was observed in the wheat which followed rice and it was equivalent to 40 kg N ha−1 plus some P applied directly to wheat.
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    URL: http://dx.doi.org/10.1007/BF01986279
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    Balanced pasture fertilization in the Basque Country: I. Phosphorus and potassium budgets on dairy farms (1996)
    Springer
    Nutrient cycling in agroecosystems 47 (1996), S. 261-269 
    Details
    ISSN: 1573-0867
    Keywords: pasture fertilization ; phosphorus ; potassium ; nutrient budget ; nutrient efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Dairy farming is the main agricultural activity of the Basque Country. A dairy farm is characterized as a system with soils and crops, forage, cattle and manure as main components, and in such a system, nutrient cycling is very important to maintain soil fertility and optimize forage production. To quantify nutrient transfers in the cycle, a simple system was developed and has been applied to seventeen farms to examine its ability to achieve a balanced P and K fertilization. These farms have provided data on inputs (fertilizer, feeds, concentrates), pasture and manure management, and outputs (milk production), and soil samples have been taken from farm pastures. Phosphorus and K in excreta and uneaten pasture is used with a relatively high efficiency as suggested by the relatively high efficiency of P and K utilization by the pasture that usually ranges from 70 to 90%. Concentrate feeding (3000 kg cow−1 yr−1) represents one of the main P and K inputs in Basque Country dairy farms, averaging 26 and 66 kg ha−1, respectively. Besides, release of K in the soil through slow liberation from non-exchangeable sites was estimated as 30 kg ha−1. Thus, a high efficiency in excreta recycling would diminish substantially P and K mineral fertilizer needs. Farm nutrient budgets appear to be a convenient tool for determining nutrient shortages and surpluses at farm level, and thus they are considered as a first step to support a better management of maintenance fertilization of permanent pastures.
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    Nitrogen fertilizer use in rainfed agriculture (1984)
    Springer
    Nutrient cycling in agroecosystems 5 (1984), S. 371-382 
    Details
    ISSN: 1573-0867
    Keywords: nitrogen ; phosphorus ; dry areas ; apparent recovery fraction ; fertilizer management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agronomic efficiency (AE) is defined as the increase in economic yield of a crop per unit fertilizer applied. Components of AE are physiological efficiency and apparent recovery fraction. The latter can be further separated into uptake efficiency and availability index. Ways to increase the nitrogen fertilizer use efficiency in rainfed agriculture through fertilizer management are discussed.
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    URL: http://dx.doi.org/10.1007/BF01049117
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    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.
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    URL: http://dx.doi.org/10.1007/BF00750462
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    The effect of ionic strength on soil P reactions is negligible (1995)
    Springer
    Nutrient cycling in agroecosystems 45 (1995), S. 193-197 
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    ISSN: 1573-0867
    Keywords: cation activity ; phosphorus ; potassium chloride ; soil solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The electrolyte concentration of the soil solution affects the availability of some nutrients in the soil, especially of P, but it is not know at what salt concentration the reactions start to be significantly affected and their magnitude. This study was carried out to evaluate the effect of rates of potassium chloride (KCl) on some soil parameters that determine supplying of P, K, Ca, Mg, and Al in an unlimed acid soil. Increasing rates of KCl (from zero up to 2000 mg K kg−1) were applied to soil samples fertilized with 360 mg P kg−1. Solution (Cli) and exchangeable (Csi) forms of P, Ca, Mg, K, and Al were determined in the treated soil samples after 30-days of incubation; cation activity in solution and their selectivity coefficients were then calculated. Addition of KCl at rates equal to or above 500 mg K kg−1 caused a large relative increase on P in the soil solution (Pli) but a small and insignificant increase on the absolute value of Pli. All forms of soil K increased with increases on K applied, and buffer power for K varied according to the range of soil K. At all KCl rates, K displaced Ca, Mg, and Al from the solid phase to the soil solution, but had no effect on the extractable values. The relative preference of cations for the adsorption sites increased with increase on cation valency, and only those selectivity coefficients involving K were affected by K applied.
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    URL: http://dx.doi.org/10.1007/BF00748589
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    Estimating nutrient surplus and nutrient use efficiency from farm characteristics (1995)
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    Nutrient cycling in agroecosystems 45 (1995), S. 221-233 
    Details
    ISSN: 1573-0867
    Keywords: fertilizer recovery ; modelling ; nitrogen ; nutrient efficiency ; nutrient surplus ; phosphorus ; Poland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Research on nutrient losses from agricultural systems should try to relate these losses to farm characteristics. This was done for private farms in two districts in Poland. Using data from a farm survey, nutrient surpluses and Nutrient Use Efficiency (NUE, defined as the ratio of outgoing and incoming nutrients) were calculated for nitrogen and phosphorus. Both nutrient surplus and NUE are relatively high. A model was developed to estimate surpluses and NUE from farm characteristics like location, farm size, fertilizer application level, animal density, grass production and sugar beet or potato area. The results of the model are satisfying for nutrient surplus (R2=0.9) and nitrogen NUE (R2=0.4). Estimation of phosphorus NUE was not satisfactory. High surpluses are associated with high fertilizer applications, high animal density and high grass production while an increasing share of sugar beets leads to lower surpluses. A high nitrogen NUE is associated with low fertilizer applications, low animal density and little grass production, and with a high sugar beet area share. Results suggest that, with exception of sugar beet, fertilizer recovery in Poland is very low. Sugar beet, however, combines high fertilizer applications with low surpluses and high NUE. The outcome of the model can be used in the design of environmental policies. The paper ends with some remarks on the type of measures that can be taken, and the effects these will have on private farms in Poland.
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    URL: http://dx.doi.org/10.1007/BF00748593
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    Influence of co-granulated nutrients and granule size on plant responses to elemental sulfur in compound fertilizers (1996)
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 81-90 
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    ISSN: 1573-0867
    Keywords: elemental sulfur ; granule size ; nitrogen ; phosphorus ; potassium ; S oxidation ; sulfur fertilizers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were undertaken to determine the effect of granule size and nutrients in granulated compound fertilizers fortified with finely divided elemental sulfur (So) on the rate of So oxidation. In one experiment, So was banded together with or apart from triple superphosphate (TSP) while in two others, So was granulated with nutrient and inert carriers. A fourth experiment examined response to S in an So-fortified TSP from a range of granule sizes. Response and, in some cases, So recovery (using 35S labels) by test crops (maize, wheat, upland rice) was measured. In all experiments, P mixed with So increased plant growth and S recovery above treatments in which P and So were physically separated. There was however, no effect of distance of separation on S recovery. In one experiment, N as urea and N and P as diammonium phosphate (DAP) were also found to enhance response to So although to a lesser degree than P alone. These observations were attributed to a nutritional requirement of So-oxidizing microorganisms for P and N. Granulation of So with carriers also influenced oxidation rate, as inferred from the fertilizer S recovery. For a given So concentration, the effect was inversely proportional to the mean diameter of granules. It is shown that this relationship can be explained if one assumes that So particles in granules collapse into a fixed number of aggregates per granule irrespective of granule size when the soluble nutrient carrier dissolves and diffuses away from the point of application.
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    URL: http://dx.doi.org/10.1007/BF00210226
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    Characterization of soil-fertilizer P reaction products and their evaluation as sources of P for gram (Cicer arietinum L.) (1996)
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 71-79 
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    ISSN: 1573-0867
    Keywords: ammonium poly-phosphate ; diammonium orthophosphate ; fertilizer reaction ; gram ; Indian soils ; phosphorus ; P uptake ; single superphosphate ; triple superphosphate ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Laboratory studies on the characterization of soil-fertilizer P reaction products were carried out by reacting three-soils occurring in a toposequence in the plateau region of Bihar (India) with saturated solutions of diammonium orthophosphate (DAP), triple superphosphate (TSP) and ammonium polyphosphate (APP) for 1 hour and 24 hours. The reaction products (precipitates) formed in the solutions after 120 days of incubation were isolated and identified through X-ray diffraction technique. Results indicate the formation of Brushite [CaHPO4 · 2H2O, Strengite (FePO4 · 2H2O), Variscite (AIPO4 · 2H2O) and Fe4(P2O7)3 as major soil-fertilizer P reaction products in these soils with ortho-and polyphosphates as source of phosphorus. Pot cultures were used to evaluate the relative efficiency of reaction products (Struvite, Brushite, Variscite and Strengite), orthophosphates (DAP and SSP) and polyphosphate (APP) as sources of P for gram (Cicer arietinum L.) in a typical acid soil. Results indicate significant response of gram to different sources and level of added P. The dry weight and P uptake at 0, 6 and 12 mg P kg-1 soil were 0.406, 0.519 and 0.609 (g pot-1); and 0.289, 0.428 and 0.575 (mg P pot-1), respectively. Among the sources , struvite proved to be superior or equally effective as APP, DAP or SSP as sources of P for gram. Uptake of P also varied significantly with different P sources and levels of P application. Strengite was least effective in enhancing yield and P uptake by the crop.
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    Fertilizer inputs, nutrient balance and soil nutrient supplying power in intensive, irrigated rice system. III. Phosphorus (1996)
    Springer
    Nutrient cycling in agroecosystems 46 (1996), S. 111-125 
    Details
    ISSN: 1573-0867
    Keywords: long-term experiments ; phosphorus ; rice ; nutrient balance ; phosphorus uptake ; fertilizer P response ; soil testing ; ion-exchange resin ; phosphorus supplying capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Data from long-term experiments at 11 sites in Asia with a wide range of nutrient input treatments and yield levels were used to quantify crop P requirements of rice (Oryza sativa L.) and the P balance in intensive, irrigated rice systems. Uptake of 1.8–4.2 kg P was required to produce one ton of grain yield. Physiological P use efficiency varied between 220 to 900 kg grain kg P-1. Without added P, there was a net loss of 7 to 8 kg P ha-1 per crop; with added P there was a net gain of 4 to 5 kg P ha-1 per crop. Phosphorus adsorption kinetics on mixed-bed ion-exchange resin capsules provided an integrative measure of soil P status, P diffusion, and acid-induced P solubilization. The resin capsule was a sensitive tool to characterize buildup or depletion of soil P as a result of different P balances. Both Olsen-P and the resin capsule were suitable methods to predict P uptake of tropical lowland rice. It is hypothesized that both methods measure a similar soil P pool which is soluble under alkaline, aerobic conditions but transformed into acid-soluble P froms as a result of submergence and reduction. Present recommendations for P fertilizer use on rice of 20–25 kg P ha-1 are adequate to maintain yields of 5–6 t ha-1, but sustaining higher yields of 7–8 t ha-1 will require farm-specific management strategies based on knowledge of the long-term P balance and soil P-supplying capacity.
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    Fertilizing programs (1985)
    Springer
    Nutrient cycling in agroecosystems 8 (1985), S. 39-47 
    Details
    ISSN: 1573-0867
    Keywords: economics ; fertilizer residues ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Alternative programs for applications of fertilizer phosphorus to successive crops are computed from the data of long term experiments showing the effects of fresh fertilizer applications and of residues from applications to previous crops on the yields of wheat in Australia and of soybeans in Brazil. The programs are compared on the basis of total economic returns with allowance for the time scale for investments in fertilizer and returns from the successive crops. Gains from the use of optimal programs may be small relative to those obtained with normal farm practice for conditions of moderate fertilizer requirement as represented by the Australian experiments, but may be appreciable for soils with high requirements as in the Cerrados region of Brazil. Estimates of optimal programs may be much affected by variations in yield levels and yield responses to fertilizer due to variations in year to year growing conditions, and it is concluded that long term fertilizer experiments are not likely to provide practicable bases for estimating programs for use by farmers. There is need to develop alternative procedures for estimating optimal programs such as might be based on effects of fertilizer on soil composition.
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    Fertilizer and liming value of lime-treated sewage sludge (1986)
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    Nutrient cycling in agroecosystems 8 (1986), S. 313-328 
    Details
    ISSN: 1573-0867
    Keywords: fertilizers ; lime ; lucerne ; nitrogen ; phosphorus ; sewage sludge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment was conducted with lucerne on a strongly acidic and phosphorus deficient soil to determine the liming and phosphorus and nitrogen fertilizer value of an undigested, lime-treated sewage sludge. The results are presented in terms of calculated combinations of lime, nitrogen and phosphorus fertilizer required to obtain the same lucerne yield (or soil pH or extractable phosphorus level) as achieved with 5 or 10 t ha−1 of dried sludge. The sludge was a good source of lime, phosphorus and nitrogen. The sludge phosphorus was 49% as effective as the fertilizer phosphorus in raising extractable phosphorus in the soil to the level required for crop growth. The calcium carbonate of the sludge raised soil pH more effectively than agricultural lime, probably because of finer particle size in the former. It was not possible to achieve the yield obtained with 25 t ha−1 of sludge with combinations of agricultural lime, and nitrogen and phosphorus fertilizers at high rates of application. This was attributed to the effects of the sludge on improving soil physical properties.
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    Comparisons of the fertilizing and liming properties of lime-treated sewage sludge with its incinerated ash (1986)
    Springer
    Nutrient cycling in agroecosystems 9 (1986), S. 187-197 
    Details
    ISSN: 1573-0867
    Keywords: lime ; lucerne ; nitrogen ; phosphorus ; ryecorn ; ryegrass ; sewage sludge ; sewage ash
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two field experiments were conducted to compare the fertilizing and liming properties of dried lime-treated sewage sludge with its incineration product (ash). One experiment used a mixture of ryecorn and ryegrass on a relatively fertile soil and the other lucerne on a strongly acidic and phosphorus deficient soil. The first harvest of the ryecorn-ryegrass experiment showed small but significant linear responses in dry matter yield to both ash and sludge. Ash applications did not affect foliage nitrogen and phosphorus concentrations, or uptakes, but sludge applications increased these significantly. Sludge also increased the concentrations of K, S, Mg, Cu and Zn but ash only increased the concentrations of S and Mg. At the second harvest (ryegrass) 5 t ha−1 of sludge increased dry matter yield and foliage nitrogen and phosphorus concentrations whereas ash had no effect. Levels of phosphorus extracted from the soil were increased by both amendments but the sludge was much more effective than the ash. Both ash and sludge raised soil pH. In the lucerne experiment comparisons between sludge and ash were calculated from response surfaces fitted to the data which showed marked increased in soil pH and dry matter yield. Sludge markedly increased extractable phosphorus whereas ash had no effect. The sludge was 22% as effective as ash in raising soil pH to 6.5. The amounts of ash required to obtain the same yield as 10 t ha−1 of sludge were 5.78, 12.78 and 6.39 t ha−1 respectively for three successive harvests. These results and those for foliage concentrations of nitrogen and phosphorus were also ascribed to the much greater availability of the sludge phosphorus than the ash phosphorus, and the presence of nitrogen in the sludge but not in the ash.
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    Nutrient losses in surface and subsurface flow from pasture applied poultry litter and composted poultry litter (1998)
    Springer
    Nutrient cycling in agroecosystems 50 (1998), S. 287-290 
    Details
    ISSN: 1573-0867
    Keywords: hydrology ; solute transport ; nitrate ; phosphorus ; polypedon scale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Over application of poultry litter may cause pollution of surface and ground water. Spatial variability in soil characteristics makes predictions difficult. Composting poultry litter could reduce the risk of pollution by creating more stable organic components. Three rates of poultry litter and compost (10 Mg ha-1 litter, 20 Mg ha-1 litter and 10 Mg ha-1 litter combined with 50 Mg ha-1 compost) to three watersheds under pasture. The watersheds were monitored for surface and subsurface flow. Nitrate-N concentrations in subsurface flow did not exceed the U.S. Environmental Protection Agency drinking water standard of 10 mg L-1. Soluble phosphorus concentrations in runoff were high, reaching a maximum of 8.5 mg L-1 under the compost treatment. These concentrations are generally lower than reported on smaller scale studies, which shows the need of studies at the correct scale.
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    URL: http://dx.doi.org/10.1023/A:1009760832696
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    Modern and historic accumulation rates of phosphorus in Lake Okeechobee, Florida (1998)
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    Journal of paleolimnology 20 (1998), S. 31-46 
    Details
    ISSN: 1573-0417
    Keywords: phosphorus ; Lake Okeechobee ; lead-210 dating ; eutrophication ; phosphorus loading
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Phosphorus accumulation rates in depositional zone sediments of Lake Okeechobee were determined in 11 mud-zone cores and two peat-zone cores dated by 210Pb. Although difficulties were encountered in interpreting 210Pb data from some sites, reliable dating of sediments from the mud zone of this shallow lake is possible. Sediment accumulation rates in this zone have increased during the present century by an average of about twofold, and accumulation of organic sediments in the lake during pre-settlement times apparently was much slower than during the past century. Concentrations of all forms of sedimentary P but especially nonapatite inorganic-P and organic-P also have increased since pre-settlement times and especially since about 1940. Annual P accumulation rates in the lake's sediments have increased about fourfold during the 1900s, with most of the increase occurring in the past 40–50 years. The recent accumulation rate of sedimentary P (past ~ 10 years) agrees within a factor of 1.5 with the net retention of P in the lake calculated from published input-output mass balances.
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    Variability of diatom-inferred phosphorus profiles in a small lake basin and its implications for histories of lake eutrophication (1998)
    Springer
    Journal of paleolimnology 20 (1998), S. 47-55 
    Details
    ISSN: 1573-0417
    Keywords: diatoms ; spatial variability ; canonical correspondence analysis ; lake eutrophication ; transfer functions ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Diatom analyses were undertaken of sediment cores covering a range of water depths in a small eutrophic lake (Lough Augher, Co. Tyrone, N. Ireland). The significance of between-core variability in diatom relative frequency stratigraphy was assessed by Canonical Correspondence Analysis (CCA) where the ordination axes were constrained to external environmental variables (sediment depth, core location coordinates, water depth, effective fetch, distance-from-shore and distance-from-inflow). After the removal of the effect of sediment age by partialling it out, the resultant first two axes from the partial-CCA were significantly correlated with water depth and distance-from-shore, indicating non-uniform diatom stratigraphies across the lake. Despite this variability, all cores show the same succession of species and, therefore, record the eutrophication of the lake. Diatom-inferred total phosphorus (DI-TP) was inferred for six cores using weighted averaging regression and calibration. Apart from considerable differences of DI-TP in surficial sediment samples, there was good between-core repeatability of DI-TP profiles. These data support the use of DI-TP for establishing background nutrient concentrations for lakes, and associated implications for lake restoration schemes using single cores. Comparisons of DI-TP profiles and total diatom accumulation rate data for the individual cores indicate that diatom production peaked prior to the maximum TP concentrations in the lake.
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    The determination of phosphonate base scale inhibitors in brines by plasma spectrometry (1992)
    Springer
    Microchimica acta 109 (1992), S. 201-209 
    Details
    ISSN: 1436-5073
    Keywords: phosphonate base scale inhibitor ; brine ; direct current plasma ; inductively coupled plasma atomic emission spectrometry ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The determination of phosphonate base scale inhibitors in brines by direct current plasma (DCP) and inductively coupled plasma atomic emission spectrometry (ICP-AES) is described. The first method is based on a direct nebulization of the brine samples and plasma using the phosphorus line at 213.618 nm. The second method involves extraction of phosphorus as phospho-antimonyl molybdate complex into methylisobutyl ketone (MIBK) phase and analysis of the extract for molybdenum using the Mo 313.260 nm line. Comparison between the proposed methods and an established recommended method [1] shows excellent agreement between the results in addition to the sensitivity and ease of automation provided by AES.
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    The anthropic catchment-ecosystem concept: An Irish example (1985)
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    Human ecology 13 (1985), S. 209-240 
    Details
    ISSN: 1572-9915
    Keywords: catchment-ecosystem ; nutrient-budget ; anthropogenic inputs ; nitrogen ; phosphorus ; eutrophication ; agricultural policies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract The catchment-ecosystem concept is adapted to investigate the nutrient-budget of the highly-modified Colebrooke drainage basin in Northern Ireland. Anthropogenic inputs, mainly manures and fertilizers, account for 86% of the nitrogen and 96% of the phosphorus added to the catchment. These inputs greatly exceed the streamflow outputs, thereby indicating that the flow of nutrients is dominated by agriculture. This is explained by the transformation of traditional mixed farming into more intensive livestock production and is linked to policies encouraging increased agricultural production, amalgamation of farms, afforestation, rural depopulation, and urbanization. Substantial increases in the Nand Poutput of the catchment and further eutrophication of the recipient lake, Lough Erne, are predicted without the implementation of policies to reduce agricultural nutrient losses.
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    Simulation of drainage water quality with DRAINMOD (1995)
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    Irrigation and drainage systems 9 (1995), S. 259-277 
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    ISSN: 1573-0654
    Keywords: drainage ; controlled drainage ; DRAINMOD ; water table management ; model ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The design and management of drainage systems should consider impacts on drainage water quality and receiving streams, as well as on agricultural productivity. Two simulation models that are being developed to predict these impacts are briefly described. DRAINMOD-N uses hydrologic predictions by DRAINMOD, including daily soil water fluxes, in numerical solutions to the advective-dispersive-reactive (ADR) equation to describe movement and fate of NO3-N in shallow water table soils. DRAINMOD- CREAMS links DRAINMOD hydrology with submodels in CREAMS to predict effects of drainage treatment and controlled drainage losses of sediment and agricultural chemicals via surface runoff. The models were applied to analyze effects of drainage intensity on a Portsmouth sandy loam in eastern North Carolina. Depending on surface depressional storage, agricultural production objectives could be satisfied with drain spacings of 40 m or less. Predicted effects of drainage design and management on NO3-N losses were substantial. Increasing drain spacing from 20 m to 40 m reduced predicted NO3-N losses by over 45% for both good and poor surface drainage. Controlled drainage further decreases NO3-N losses. For example, predicted average annual NO3-N losses for a 30 m spacing were reduced 50% by controlled drainage. Splitting the application of nitrogen fertilizer, so that 100 kg/ha is applied at planting and 50 kg/ha is applied 37 days later, reduced average predicted NO3-N losses but by only 5 to 6%. This practice was more effective in years when heavy rainfall occurred directly after planting. In contrast to effects on NO3-N losses, reducing drainage intensity by increasing drain spacing or use of controlled drainage increased predicted losses of sediment and phosphorus (P). These losses were small for relatively flat conditions (0.2% slope), but may be large for even moderate slopes. For example, predicted sediment losses for a 2% slope exceeded 8000 kg/ha for a poorly drained condition (drain spacing of 100 m), but were reduced to 2100 kg/ha for a 20 m spacing. Agricultural production and water quality goals are sometimes in conflict. Our results indicate that simulation modeling can be used to examine the benefits of alternative designs and management strategies, from both production and environmental points-of-view. The utility of this methodology places additional emphasis on the need for field experiments to test the validity of the models over a range of soil, site and climatological conditions.
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    The influence of a deep-storage reservoir on the physicochemical limnology of a Central Texas River (1974)
    Springer
    Hydrobiologia 44 (1974), S. 177-207 
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    ISSN: 1573-5117
    Keywords: Impoundment ; reservoir ; physicochemical limnology ; eutrophication ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study was conducted to determine a physicochemical profile of a new deep-storage reservoir and to determine the influence of impoundment and thermal stratification in the reservoir on the physicochemical limnology of the parent river. The presence of thermal stratification from May through November caused the most significant change in water conditions. Of 23 parameters studied, 12 remained unchanged, 10 improved, and 2 deteriorated (Table VI). The greatest downstream changes in water conditions from those upstream from the reservoir were a decrease in temperature, an increase of ammonia, and the presence of hydrogen sulfide during the period of thermal stratification. Ammonia did not increase to a level considered to be toxic to aquatic species. It could, however, serve as a nutrient for certain species of plants and result in a change in community structure. Water tempeature downstream from the reservoir was always within the annual temperature range of the river upstream from the reservoir; however, the summer maximum in the tailrace was decreased to a temperature that could interfere wih the normal life cycle of many species.
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    The influence of chironomus plumosus larvae on the exchange of dissolved substances between sediment and water (1979)
    Springer
    Hydrobiologia 66 (1979), S. 149-159 
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    ISSN: 1573-5117
    Keywords: Chironomus ; sediment ; exchange ; nitrogen ; phosphorus ; silica ; iron ; manganese
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 4th instar Chironomus plumosus larvae (about 1000·m−2) were added to tubes containing sediment and overlying water. At a temperature of 20°C the larvae greatly increased the trasnport of silica, phosphorus and iron from the sediment to the water. Oxygen concentrations did not influence the exchange of silica. For two non-calcareous sediments the exchange of phosphorus and iron was much higher under anaerobic than under aerobic conditions while the difference was small for sediment from a hardwater lake. Exchange of inorganic nitrogen was little influenced by added chironomid larvae.
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    Phytoplankton production and phosphorus supply in Cayuga Lake (1968–1973) (1977)
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    Hydrobiologia 54 (1977), S. 113-127 
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    ISSN: 1573-5117
    Keywords: primary production ; phosphorus ; zooplankton phosphorus release ; phosphorus loading ; 14C uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The average annual rate of carbon production in Cayuga Lake, New York, was determined by 14C uptake and by a phosphorus supply method. The rate of phosphorus supply was converted to units of carbon production using observed sestonic C : P ratios. The two methods gave good agreement and annual carbon production was estimated to be 130 gC m−2 yr−1.
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    Epilimnetic nutrient loading by metalimnetic erosion and resultant algal responses in Lake Waramaug, Connecticut (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 501-510 
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    ISSN: 1573-5117
    Keywords: phosphorus ; nutrient cycling ; stratification ; epilimnion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phosphorus regeneration from lake sediments, and subsequent migration to trophogenic surface water, significantly contributes to the lake nutrient budgets and algal bloom conditions in some lake types. Decomposition of organic matter in deep water and sediments results in the accumulation of regenerated nutrients, alternate electron acceptors (reduced products of anaerobic respiration = COD), carbon dioxide, and depletion of dissolved oxygen (electron acceptor in aerobic respiration). Thermal stratification creates spatial segregation of trophogenic and tropholytic environments in the lake, resulting in gradients between sediments, hypolimnion, and the epilimnion. Exchange of oxygen, nutrients, and reduced alternate electron acceptors between the hypolimnion and epilimnion affects the productivity of a lake. Secchi depth, temperature, and dissolved oxygen profiles were determined twice each week from May 1980 to October 1980 at each of five lake stations. Nutrient concentration profiles, including total soluble and total phosphorus, ammonium-N, nitrate, soluble Kjeldahl, and total Kjeldahl nitrogen were determined twice each month. Epilimnetic algal samples were collected twice each week using Kemmerer and water column ‘straw’ amplers. Cell counts of total, green, bluegreen, and diatom algae groups were made. Three methods were used to describe hypolimnetic-epilimnetic exchange, including coefficients of eddy diffusion (based on lake heat budget), a graphical method of defining thermocline location, and relative thermal resistance to mixing (RTRM, based on density differences). All three methods yeilded comparable estimates of net seasonal transport. The graphical and RTRM methods described events occurring at shorter intervals (greater resolution). We find general agreement between the three methods of describing hypolimnetic-epilimnetic transport. The frequency of sampling resulted in increased resolution of thermal profiles (in time), allowing accurate estimation of short-term nutrient flux into epilimnetic waters. An algal bloom event occurred 5 to 12 days following erosion of the top of the metalimnion to below the aerobic-anaerobic interface. The lag time to peak algal concentration, following such events, decreased through the summer (June = 12 days, September = 5 days)
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    Mineral composition of Phragmites australis in Scottish lochs as related to eutrophication. I. Seasonal changes in organs (1981)
    Springer
    Hydrobiologia 85 (1981), S. 227-237 
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    ISSN: 1573-5117
    Keywords: chemical composition ; eutrophication ; nitrogen ; phosphorus ; Phragmites australis ; Scottish lochs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Monthly levels of nitrogen, phosphorus, potassium, sodium, calcium, magnesium and iron in the organs (root, rhizome, stem, leaf and panicle) of Phragmites australis were determined from March to November, 1975 in Forfar Loch (polytrophic), Balgavies Loch (eutrophic) and Loch of the Lowes (mesotrophic), Scotland. Generally no consistent seasonal changes in the mineral levels were detected for the root, rhizome and panicle. For the stem and leaf, the levels of nitrogen, phosphorus, potassium, calcium and magnesium rose to a peak before declining for the rest of the season. Consistently higher levels of tissue nitrogen, phosphorus, potassium and calcium were found in the Forfar plants over those of Balgavies and Lowes, reflecting the very eutrophic condition in Forfar Loch. The mineral compositions in the reeds in the present study were compared with similar studies in other areas.
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    Algal-availability of particulate phosphorus from diffuse and point sources in the lower Great Lakes basin (1982)
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    Hydrobiologia 91-92 (1982), S. 111-119 
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    ISSN: 1573-5117
    Keywords: phosphorus ; bioavailability ; point source ; diffuse source ; Great Lakes ; bioassay ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Control of phytoplankton production in the Great Lakes can be achieved most efficiently by limiting inputs of biologically available P. We report the results of studies performed to characterize the chemical forms and availability of particulate P in wastewater and tributaries which enter the lower Lakes, the eroding bluffs which border Lake Erie, and bottom samples from the near-shore of western Lake Erie. Rates of release of available P were estimated from a simple first-order model of the process, as observed during algal bioassays. Available P in wastewater samples, as a fraction of total particulate P, was affected minimally by wastewater treatment, including chemical precipitation and filtration; it correlated well with levels of total particulate P. Available particulate P levels in fluvial suspended sediments showed regional uniformity, but appeared to be strongly dependent on levels of both NaOH-P and CDB-P. Rates of release of available P decreased during wastewater treatment to values which were similar in magnitude to those observed for fluvial sediments. Release rates, however, were not related to any of the particulate P fractions which were measured. Analysis of the bluff and bottom samples indicated that P availability in the former was negligible, but the latter contained levels which approached those of wastewater particulates, though available P was released from the bottom sediments at relatively low rates.
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    Modelling the influence of bioturbation on the vertical distribution of sedimentary phosphorus in L. Esrom (1982)
    Springer
    Hydrobiologia 91-92 (1982), S. 197-206 
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    ISSN: 1573-5117
    Keywords: bioturbation ; modelling ; sediment ; phosphorus ; Chironomus anthracinus ; Potamothrix hammoniensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A multilayer sediment-water exchange model was used to evaluate the importance of bioturbation in the profundal sediments of L. Esrom. The temporal variation of the vertical distribution of sedimentary phosphorus fractions was modelled with an objective function of 1.50. Deviations between measured and simulated values occurred in the spring, where the measured pool of sedimentary phosphorus sharply declined in the surface sediments. The application of a model for the activity ofChironomus anthracinus based on biomass, oxygen consumption and temperature improved the model in the spring period. The downwards transport of easy-degradable surface sediments reduced the average release of sedimentary phosphorus from 12 mg P · m−2 · day−1 to 11 mg P · M−2 · day−1. The introduction of a similar model for the other important burrowing species in L. Esrom,Potamothrix hammoniensis, lowered the objective function to 1.37 and increased the average release to 12.5 mg P · m−2 · day−1. The minor role of bioturbation in sediment processes is discussed.
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    An analysis of total phosphorus transport in river systems (1982)
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    Hydrobiologia 91-92 (1982), S. 241-252 
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    ISSN: 1573-5117
    Keywords: pollution ; rivers ; transport ; calculation ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Human activities generate many pollutants from different land uses. These pollutants include nutrients (e.g., phosphorus and nitrogen), toxic substances (e.g., heavy metals and pesticides), and other substances (e.g., chlorides and salts). These materials often enter a river at some upstream point and are transported downstream by the flowing water. Many substances are transported both during storms and during normal river flow and often the major portion of the transport occurs during the storms. This paper considers the quantification of transport primarily during storms. First, the characteristics of storm transport are discussed. Then, a calculation method for estimating the distance of travel for sediment related materials is presented. Third, a technique to estimate the amount of a given chemical passing a point in a stream over a specified period of time is presented. The last part of this paper contains a technique for tracing the movement of substances through a river network. In particular, this procedure yields information as to the source of given pollutants over the entire Storm period.
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    Algal-availability of particulate phosphorus from diffuse and point sources in the lower Great Lakes basin (1982)
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    Hydrobiologia 91-92 (1982), S. 111-119 
    Details
    ISSN: 1573-5117
    Keywords: phosphorus ; bioavailability ; point source ; diffuse source ; Great Lakes ; bioassay ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Control of phytoplankton production in the Great Lakes can be achieved most efficiently by limiting inputs of biologically available P. We report the results of studies performed to characterize the chemical forms and availability of particulate P in wastewater and tributaries which enter the lower Lakes, the eroding bluffs which border Lake Erie, and bottom samples from the near-shore of western Lake Erie. Rates of release of available P were estimated from a simple first-order model of the process, as observed during algal bioassays. Available P in wastewater samples, as a fraction of total particulate P, was affected minimally by wastewater treatment, including chemical precipitation and filtration; it correlated well with levels of total particulate P. Available particulate P levels in fluvial suspended sediments showed regional uniformity, but appeared to be strongly dependent on levels of both NaOH-P and CDB-P. Rates of release of available P decreased during wastewater treatment to values which were similar in magnitude to those observed for fluvial sediments. Release rates, however, were not related to any of the particulate P fractions which were measured. Analysis of the bluff and bottom samples indicated that P availability in the former was negligible, but the latter contained levels which approached those of wastewater particulates, though available P was released from the bottom sediments at relatively low rates.
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    Colonisation par les micro-organismes, evolution chimique des feuilles de différentes espèces d'arbres (peuplier, aulne, myrique) dans des eaux oligotrophes du Bouclier canadien et incidence sur leur utilisation par les macro-invertébrés (1982)
    Springer
    Hydrobiologia 96 (1982), S. 65-75 
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    ISSN: 1573-5117
    Keywords: leaf-conditioning ; microorganisms ; nitrogen ; carbon ; phosphorus ; Alnus rugosa ; Populus tremuloides ; Myrica gale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Myrica gale, Alnus rugosa and Populus tremuloides leaves were incubated ‘in situ’ in the oligotrophic acid waters of the Canadian Shield (James Bay, Quebec) in order to follow microorganic decomposition, respiration and chemical transformations. Respiratory activities in decomposing speckled alder and trembling aspen leaves were more important than that in sweet gale. In spite of low nutrient concentrations in the water, nitrogen concentration increased in the three species while phosphorus levels increased only in the speckled alder during decomposition.
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    Kinetics of nitrogen and phosphorus release in varying food supplies byDaphnia magna (1982)
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    Hydrobiologia 96 (1982), S. 105-111 
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    ISSN: 1573-5117
    Keywords: nitrogen ; phosphorus ; exrretion ; food quality ; zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rates of nitrogen and phosphorus release from individualDaphnia magna were determined by measuring ammonia and soluble reactive phosphorus in successive 10-min incubations in small (0.05 ml) vessels after the animals were removed from their food. Release rates of both nutrients were generally highest initially and decreased with time after removal. The ratio of nitrogen to phosphorus released increased with time after animals were removed from an artificial detritus/bacterial food; ratios were lower and changed with time less for animals fed algae. These data suggest errors may be introduced by assumptions of constant stoichiometry for nutrient release in varying environments.
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    Phosphorus limitation of forest leaf area and net primary production on a highly weathered soil (1995)
    Springer
    Biogeochemistry 29 (1995), S. 223-235 
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    ISSN: 1573-515X
    Keywords: chronosequence ; montane tropical forest ; nitrogen ; nutrient limitation ; phosphorus ; productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We tested the hypothesis that P was the nutrient limiting net primary production of a nativeMetrosideros polymorpha forest on a highly weathered montane tropical soil in Hawaii. A factorial experiment used all combinations of three fertilizer treatments: nitrogen (N), phosphorus (P) and a mix of other essential nutrients (OE), consisting primarily of mineral derived cations and excluding N and P. P addition, but not N or OE, increased leaf area index within 12 months, foliar P concentration measured at 18 months, and stem diameter increment within 18 months. Stem growth at 18 months was even greater when trees fertilized with P also received the OE treatment. N and P additions increased leaf litterfall and N and P in combination further increased litterfall. The sequence of responses suggests that increased available P promoted an increase in photosynthetic area which led to increased wood production. P was the essential element most limiting to primary production on old volcanic soil in contrast to the N limitation found on young volcanic soils.
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    The fate of nitrogen and phosphorus at the land-sea margin of the North Atlantic Ocean (1996)
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    Biogeochemistry 35 (1996), S. 141-180 
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    ISSN: 1573-515X
    Keywords: continental shelf ; estuaries ; mass balance ; nitrogen ; North Atlantic ; nutrient budget ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Five large rivers that discharge on the western North Atlantic continental shelf carry about 45% of the nitrogen (N) and 70% of the phosphorus (P) that others estimate to be the total flux of these elements from the entire North Atlantic watershed, including North, Central and South America, Europe, and Northwest Africa. We estimate that 61 · 109 moles y−1 of N and 20 · 109 moles y−1 of P from the large rivers are buried with sediments in their deltas, and that an equal amount of N and P from the large rivers is lost to the shelf through burial of river sediments that are deposited directly on the continental slope. The effective transport of active N and P from land to the shelf through the very large rivers is thus reduced to 292 · 109 moles y−1 of N and 13 · 109 moles y−1 of P. The remaining riverine fluxes from land must pass through estuaries. An analysis of annual total N and total P budgets for various estuaries around the North Atlantic revealed that the net fractional transport of these nutrients through estuaries to the continental shelf is inversely correlated with the log mean residence time of water in the system. This is consistent with numerous observations of nutrient retention and loss in temperate lakes. Denitrification is the major process responsible for removing N in most estuaries, and the fraction of total N input that is denitrified appears to be directly proportional to the log mean water residence time. In general, we estimate that estuarine processes retain and remove 30–65% of the total N and 10–55% of the total P that would otherwise pass into the coastal ocean. The resulting transport through estuaries to the shelf amounts to 172–335 · 109 moles y−1 of N and 11–19 · 109 moles y−1 of P. These values are similar to the effective contribution from the large rivers that discharge directly on the shelf. For the North Atlantic shelf as a whole, N fluxes from major rivers and estuaries exceed atmospheric deposition by a factor of 3.5–4.7, but this varies widely among regions of the shelf. For example, on the U.S. Atlantic shelf and on the northwest European shelf, atmospheric deposition of N may exceed estuarine exports. Denitrification in shelf sediments exceeds the combined N input from land and atmosphere by a factor of 1.4–2.2. This deficit must be met by a flux of N from the deeper ocean. Burial of organic matter fixed on the shelf removes only a small fraction of the total N and P input (2–12% of N from land and atmosphere; 1–17% of P), but it may be a significant loss for P in the North Sea and some other regions. The removal of N and P in fisheries landings is very small. The gross exchange of N and P between the shelf and the open ocean is much larger than inputs from land and, for the North Atlantic shelf as a whole, it may be much larger than the N and P removed through denitrification, burial, and fisheries. Overall, the North Atlantic continental shelf appears to remove some 700–950· 109 moles of N each year from the deep ocean and to transport somewhere between 18 and 30 · 109 moles of P to the open sea. If the N and P associated with riverine sediments deposited on the continental slope are included in the total balance, the net flux of N to the shelf is reduced by 60 · 109 moles y−1 and the P flux to the ocean is increased by 20 · 109 moles y−1. These conclusions are quite tentative, however, because of large uncertainties in our estimates of some important terms in the shelf mass balance.
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    Nutrient limitation and soil development: Experimental test of a biogeochemical theory (1997)
    Springer
    Biogeochemistry 37 (1997), S. 63-75 
    Details
    ISSN: 1573-515X
    Keywords: nutrient limitation ; soil development ; nitrogen ; phosphorus ; chronosequence ; Hawai'i
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Walker & Syers (1976) proposed a conceptual model that describesthe pattern and regulation of soil nutrient pools and availability during long-term soil and ecosystem development. Their model implies that plantproduction generally should be limited by N on young soils and by P on oldsoils; N and P supply should more or less equilibrate onintermediate-aged soils. We tested the application of this model to nutrientlimitation, using a well characterized substrate age sequence in Hawaiianmontane rain forest. Earlier experiments had evaluated nutrient limitationin forests on a young (300 y) and an old (4,100,000 y) substrate on the samedevelopmental sequence; N alone limited tree growth on the youngsubstrate, while P alone did so on the old one. An additional fertilizerexperiment based on replicated treatments with N, P, and all othernutrients combined, applied in individually and in all factorialcombinations, was established in an intermediate-aged site in theLaupahoehoe Forest Reserve, Hawaii. Here, diameter increments of thedominant tree Metrosideros polymorpha increased slightly with Nadditions, and nearly doubled when N and P were added together.Additions of elements other than N and P had no significant effecton growth. These results show that N and P had equilibrated (relativeto plant requirements) in the intermediate aged site. Together withthe earlier experiments, these results suggest that the Walker and Syersmodel provides a useful starting point for explaining the nature anddistribution of nutrient limitation in forest ecosystems.
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    Marine nitrogen: Phosphorus stoichiometry and the global N:P cycle (1997)
    Springer
    Biogeochemistry 37 (1997), S. 237-252 
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    ISSN: 1573-515X
    Keywords: freshwater ; limitation ; marine ; nitrogen ; phosphorus ; ratio ; stoichiometry ; trace elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nitrogen supply is often assumed to limitmarine primary production. A global analysis of totalnitrogen (N) to phosphorus (P) molar ratios shows thattotal N:P is low (〈16:1) in some estuarine andcoastal ecosystems, but up to 100:1 in open oceans.This implies that elements other than N may limitmarine production, except in human impacted, estuarineor coastal ecosystems. This pattern may reconcileconflicting enrichment studies, because N additionfrequently increases phytoplankton growth where totalN:P is expected to be low, but P, Fe, or Si augmentphytoplankton growth in waters where total N:P ishigh. Comparison of total N:P stoichiometry betweenmarine and freshwaters yields a model of the form ofthe aquatic N:P cycle.
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    Chesapeake Bay nutrient budgets — a reassessment (1987)
    Springer
    Biogeochemistry 4 (1987), S. 77-90 
    Details
    ISSN: 1573-515X
    Keywords: Chesapeake Bay ; nutrients ; eutrophication ; estuary ; nitrogen ; phosphorus ; silicon ; sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Recently published annual mass balances or budgets for nitrogen, phosphorus, and silicon in Chesapeake Bay have pictured the estuary as retaining a very large fraction, perhaps all, of the nutrients that enter from land drainage, the atmosphere, and anthropogenic discharges. However, these budgets have been based on estimates of the net exchanges of nutrients at the mouth of the bay or on the rates of accumulation of nutrients and sediments calculated from the distributions of various geochemical tracers in the sediments. While conceptually straightforward, the first approach is subject to large errors because it requires the determination of a small "signal" against a large background of tidal "noise". The second approach has led to overestimates of the nutrient trapping efficiency of the bay because tracer-derived sediment deposition rates have been multiplied by the surface area of the whole bay or various parts of the bay rather than by the smaller area of active sediment deposition. This approach is also incorrect because the average, long-term rates of sediment deposition measured by the geochemical tracers, including major floods, have been compared to shorter-term records of nutrient input. The more appropriate calculation of nutrient retention based on contemporaneous measurements of nutrient and sediment input and the chemical compositon of sediments accumulated in the estuary shows that Chesapeake Bay retains only some 3–6% of the nitrogen, 11–17% of the phosphorus and 33–83% of the silicon brought into its waters during a year in which no major flood occurred. This behavior suggests that current problems of estuarine eutrophication are more a consequence of present nutrient inputs than an inevitable or inescapable legacy of past enrichment. It also follows that the management or manipulation of nutrient loadings to esturies may lead to a more rapid response in environmental quality than previously predicted.
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    URL: http://dx.doi.org/10.1007/BF02187363
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  • 89
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    Modeling as a tool to manage ecosystems under multiple stresses: an application to Lake Ontario (1996)
    Springer
    Journal of aquatic ecosystem stress and recovery 5 (1996), S. 23-40 
    Details
    ISSN: 1573-5141
    Keywords: ecosystem modeling ; fishery management ; organic carbon mass balance ; stocking ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Present-day ecosystem management involves understanding of the synergistic effect of multiple stressors on multiple and frequently nebulous management end-points. An example is the simultaneous management of nutrient load reductions and salmon stocking in Lake Ontario. In this study, a simple whole-lake annual time scale model was developed to assess the relationship between these two stressors and various ecosystem responses. The model was used to explore the utility of some possible management end-points for ecosystem health. In historical simulations, production per stocked fish and salmon survival appeared to be good indicators, while nutrient recycling rate and average ecosystem-wide food limitation were found to be fairly unresponsive to the two stressors. The model was further used to predict long term averages of salmon biomass and selected health indicators at various sustained loading and stocking rates. Salmon biomass increased with stocking rate at all stocking rates examined, but the rate of increase declined somewhat at high stocking rates. The response of salmon biomass to nutrient loading appeared to be approximately sigmoidal i.e. there was a nutrient threshold below which fish biomass could not be sustained and another nutrient threshold above which salmon biomass either remained constant or even decreased. The response to either stressor was found to be modified by the value of the other stressor, illustrating the importance of ecosystem-level models for aquatic ecosystem management.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691727
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  • 90
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    Electronic Resource
    Nutrient budgets and biogeochemistry in an experimental agricultural watershed in Southeastern China (1999)
    Springer
    Biogeochemistry 45 (1999), S. 1-19 
    Details
    ISSN: 1573-515X
    Keywords: Chaohu Lake ; chemical fertilizer ; cycling ; denitrification ; multipond system ; nitrogen ; nutrient budget ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract During a two-year field study, an annual nutrient budget and cycles were developed for a small agricultural watershed. The study emphasized the integrated unit of the watershed in understanding the biogeochemistry. It was found that the total nutrient input was 39.1 × 104 kg nitrogen and 3.91 × 104 kg phosphorus in the year 1995, of which the greatest input of nutrients to the watershed was chemical fertilizer application, reaching 34.7 × 104 kg (676 kg/ha) nitrogen and 3.88 × 104 kg (76 kg/ha) phosphorus. The total nutrient output from the watershed was 13.55 × 104 kg nitrogen and 0.40 × 104 kg phosphorus, while the largest output of nitrogen was denitrification, accounting for 44.1% of N output; the largest output of phosphorus was sale of crops, accounting for 99.4% of P output. The results show that the nutrient input is larger than output, demonstrating that there is nutrient surplus within the watershed, a surplus which may become a potential source of nonpoint pollution to area waters. The research showed that both denitrification and volatilization of nitrogen are key ways of nitrogen loss from the watershed. This suggests that careful management of fertilizer application will be important for the sustainable development of agriculture. The research demonstrated that a multipond system within the watershed had high retention rate for both water and nutrients, benefiting the water, nutrient and sediment recycling in the terrestrial ecosystem and helping to reduce agricultural nonpoint pollution at its source. Therefore, this unique watershed system should be recommended due to its great potential relevance for sustainable agricultural development.
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    URL: http://dx.doi.org/10.1023/A:1006073408623
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  • 91
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    The fate of NH4NO3 added to Sphagnum magellanicum carpets at five European mire sites (1999)
    Springer
    Biogeochemistry 45 (1999), S. 73-93 
    Details
    ISSN: 1573-515X
    Keywords: atmospheric deposition ; moss ; bog ; nitrogen ; phosphorus ; water table
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nitrogen additions as NH4NO3 corresponding to 0 (N0), 1 (N1), 3 (N3) and 10 (N10) g N m-2 yr-1 were made to Sphagnum magellanicum cores at two-week intervals in situ at four sites across Europe, i.e. Lakkasuo (Finland), Männikjärve (Estonia), Moidach More (UK) and Côte de Braveix (France). The same treatments were applied in a glasshouse experiment in Neuchâtel (Switzerland) in which the water table depth was artificially maintained at 7, 17 and 37 cm below the moss surface. In the field, N assimilation in excess of values in wet deposition occurred in the absence of growth, but varied widely between sites, being absent in Lakkasuo (moss N:P ratio 68) and greatest in Moidach More (N:P 21). In the glasshouse, growth was reduced by lowering the water table without any apparent effect on N assimilation. Total N content of the moss in field sites increased as the mean depth of water table increased indicating growth limitation leading to increased N concentrations which could reduce the capacity for N retention. Greater contents of NH4+ in the underlying peat at 30 cm depth, both in response to NH4NO3 addition and in the unamended cores confirmed poor retention of inorganic N by the moss at Lakkasuo. Nitrate contents in the profiles at Lakkasuo, Moidach More, and Côte de Braveix were extremely low, even in the N10 treatment, but in Männikjärve, where the mean depth of water table was greatest and retention absent, appreciable amounts of NO3- were detected in all cores. It is concluded that peatland drainage would reduce the capture of inorganic N in atmospheric deposition by Sphagnum mosses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006133828518
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  • 92
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    The fate of NH4NO3 added toSphagnum magettanicum carpets at five European mire sites (1999)
    Springer
    Biogeochemistry 45 (1999), S. 73-93 
    Details
    ISSN: 1573-515X
    Keywords: atmospheric deposition ; moss ; bog ; nitrogen ; phosphorus ; water table
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nitrogen additions as NH4NO3 corresponding to 0 (N0), 1 (N1), 3 (N3) and 10 (N10) g N m−2 yr−1 were made toSphagnum magellanicurn cores at two-week intervalsin situ at four sites across Europe, i.e. Lakkasuo (Finland). Männikjärve (Estonia), Moidach More (UK) and Côte de Braveix (France). The same treatments were applied in a glasshouse experiment in Neuchâtel (Switzerland) in which the water table depth was artificially maintained at 7, 17 and 37 cm below the moss surface. In the field, N assimilation in excess of values in wet deposition occurred in the absence of growth, but varied widely between sites, being absent in Lakkasuo (moss N∶P ratio 68) and greatest in Moidach More (N∶P 21). In the glasshouse, growth was reduced by lowering the water table without any apparent effect on N assimilation. Total N content of the moss in field sites increased as the mean depth of water table increased indicating growth limitation leading to increased N concentrations which could reduce the capacity for N retention. Greater contents of NH4 + in the underlying peat at 30 cm depth, both in response to NH4NO3 addition and in the unamended cores confirmed poor retention of inorganic N by the moss at Lakkasuo. Nitrate contents in the profiles at Lakkasuo, Moidach More, and Côte de Braveix were extremely low, even in the N10 treatment, but in Männikjärve, where the mean depth of water table was greatest and retention absent, appreciable amounts of NO3 − were detected in all cores. It is concluded that peatland drainage would reduce the capture of inorganic N in atmospheric deposition bySphagnum mosses.
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    URL: http://dx.doi.org/10.1007/BF00992874
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  • 93
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    Distribution and speciation of phosphorus along a salinity gradient in intertidal marsh sediments (1999)
    Springer
    Biogeochemistry 45 (1999), S. 197-221 
    Details
    ISSN: 1573-515X
    Keywords: intertidal marshes ; phosphorus ; sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We examined forms of solid phosphorus fractions in intertidal marsh sediments along a salinity (0–22‰) gradient in a river-dominated estuary and in a marine-dominated salt marsh with insignificant freshwater input. Freshwater marsh sediments had the highest ratio of organic N:P of between 28:1 and 47:1 mol:mol, compared to 21:1 to 31:1 mol:mol in the saltmarshes, which is consistent with a trend toward P-limitation of primary production in freshwater and N-limitation in salt marshes. However, total P concentration, 24.7 ± 11.1 µmol P g dw-1 (±1 SD) averaged over the upper meter of sediment, was greatest in the freshwater marsh where bioavailablity of P is apparently limited. In the freshwater marsh the greatest fraction of total P (24–51%) was associated with humic acids, while the importance of humic-P decreased with increasing salinity to 1–23% in the salt marshes. Inorganic P contributed considerably less to total sediment P in the freshwater marsh (15–40%) than in the salt marshes (33–85%). In reduced sediments at all sites, phosphate bound to aluminum oxides and clays was an important inorganic P pool irrespective of salinity. Inorganic P associated with ferric iron [Fe(III)] phases was most abundant in surface sediments of freshwater and brackish marshes, while Ca-bound P dominated inorganic P pools in the salt marshes. Thus, our results showed that particle-bound P in marsh sediments exhibited changes in chemical association along the salinity gradient of an estuarine system, which is a likely consequence of changes in ionic strength and the availability of iron and calcium.
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    URL: http://dx.doi.org/10.1023/A:1006136621465
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  • 94
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    A comparison of fractionation methods for forms of phosphorus in soils (1999)
    Springer
    Biogeochemistry 47 (1999), S. 25-38 
    Details
    ISSN: 1573-515X
    Keywords: Hedley fractionation ; phosphorus ; Ruttenberg fractionation ; soil phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We used l6 soils to compare the Hedley method for soil phosphorus fractionation to an alternative method recently developed by Ruttenberg to differentiate among P fractions in marine sediments. For forms of labile and Fe-bound P in soils, these methods were poorly correlated, with the Hedley fractionation showing a greater ability to discriminate among variations in plant-available P. For Ca-bound P, total organic P, and total P, the methods were well correlated (r2 = 0.93, 0.48, 0.74, respectively), although the sum of P measured in the Ruttenberg extractions is only 45% of the total P recovered by the Hedley fractionation. The Hedley fractionation seems superior when an index of plant-available phosphorus and a separation of organic and inorganic forms is needed, whereas the Ruttenberg method allows a separation of CaCO3-bound P from apatite-P, which is potentially useful in calcareous soils.
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    URL: http://dx.doi.org/10.1023/A:1006105420235
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  • 95
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    A comparison of fractionation methods for forms of phosphorus in soils (1999)
    Springer
    Biogeochemistry 47 (1999), S. 25-38 
    Details
    ISSN: 1573-515X
    Keywords: Hedley fractionation ; phosphorus ; Ruttenberg fractionation ; soil phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We used 16 soils to compare the Hedley method for soil phosphorus fractionation to an alternative method recently developed by Ruttenberg to differentiate among P fractions in marine sediments. For forms of labile and Fe-bound P in soils, these methods were poorly correlated, with the Hedley fractionation showing a greater ability to discriminate among variations in plant-available P. For Ca-bound P, total organic P, and total P, the methods were well correlated (r2=0.93, 0.48, 0.74, respectively), although the sum of P measured in the Ruttenberg extractions is only 45% of the total P recovered by the Hedley fractionation. The Hedley fractionation seems superior when an index of plant-available phosphorus and a separation of organic and inorganic forms is needed, whereas the Ruttenberg method allows a separation of CaCO3-bound P from apatite-P, which is potentially useful in calcareous soils.
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    URL: http://dx.doi.org/10.1007/BF00993095
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  • 96
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    Al and Fe Biogeochemistry in a floodplain forest: Implications for P retention (2000)
    Springer
    Biogeochemistry 51 (2000), S. 1-32 
    Details
    ISSN: 1573-515X
    Keywords: aluminum ; floodplain forests ; iron ; organic matter ; P sorption capacity ; phosphorus ; soil ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We examined spatial and temporal variationsin soil chemistry in a floodplain forest landscape todetermine the effects of flooding on aluminum (Al) andiron (Fe) oxide biogeochemistry and inorganicphosphorus (Pi) sorption capacity. Whenpreviously sorbed Pi was considered, the sorptioncapacities of floodplain and adjacent upland soilswere comparable, suggesting that floodplain soilsrepresent a second line of defense protectingdownstream aquatic ecosystems from agriculturalrun-off. Pi sorption capacity was highlycorrelated with oxalate-extractable Al (Alo)(rs = 0.78); Alo and percent organic matter(OM) were also highly correlated (rs = 0.72),suggesting the importance of OM-Al complexes in thesesoils. The correlation of oxalate-extractable Fe(Feo) with OM (rs = 0.64) was improved(rs = 0.80) by removing lower elevation (swale)soils, suggesting that flooding inhibits theassociation of Feo with OM. Fe oxidecrystallinity decreased during seasonal flooding, buttotal extractable Fe did not change significantly. Fesolubilized during flooding was either replaced bysediment deposition (252 ± 3 mmol kg−1yr−1), and/or reprecipitated locally. Al oxidecrystallinity also decreased during flooding due to asignificant decline in NaOH-extractable Al (AlN). AlN concentrations subsequently returned topre-flooding levels, but sediment Al inputs (57 ±3 mmol kg−1 yr−1), were insufficient to account for this recovery. Observed Fetransformations suggest the importance offlooding-induced declines in soil redox potential toFe biogeochemistry; observed Al transformationssuggest the importance of complexation reactions withsoil OM to Al biogeochemistry in this floodplainforest.
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    URL: http://dx.doi.org/10.1023/A:1006302600347
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  • 97
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    Control of phosphorus homeostasis of Atlantic salmon (Salmo salar) in fresh water (1998)
    Springer
    Fish physiology and biochemistry 19 (1998), S. 83-93 
    Details
    ISSN: 1573-5168
    Keywords: phosphorus ; diet ; intestinal absorption ; renal excretion ; Atlantic salmon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies were conducted to determine the absorption, excretion and requirement of dietary phosphorus (P) by Atlantic salmon (Salmo salar). Triplicate groups of salmon parr, initial weight 15 ± 0.5±g , were fed, diets containing 4, 5, 6, 7, 8, 9, 11 and 13 mg P and 20 KJ of digestible energy (DE) per±g of diet (dry matter basis, DMB) to satiation for 16 weeks. The basal diet containing 4 mg P g-1 (0.15 mg available P per KJ DE) was supplemented with graded levels of calcium phosphate, Ca(H2PO4)2⋅H2O to formulate the eight experimental diets. The fish were reared in fresh water at a temperature of 15 °C on a 12 h photoperiod. Vertebrae ash increased from 316 to 516 mg g-1 fat-free dry matter with an increase in dietary P content. P requirement was estimated by using a four-parameter sigmoidal equation. The data suggests that a diet of 0.28 mg available P per KJ DE is needed for Atlantic salmon. Phosphate and calcium levels in plasma and bone increased, whereas levels of magnesium and liver cholecalciferol decreased, with an increase in dietary P. Phosphate excretion in urine and apparent availability of P were determined in deficient and replete fish. In deficient fish, the urine phosphate concentration was 0.10 mmol L-1 before feeding and 0.25 mmol l-1 after feeding, whereas in replete fish these concentrations were 1.09 and 5.11 mmol l-1, respectively. The increase in urine phosphate concentration was higher in replete fish than in deficient fish, however, the apparent absorption of P was found to be significantly lower in replete fish than in deficient fish. These results suggest that similarly to terrestrial vertebrates, P homeostasis in Atlantic salmon is controlled by absorption in the intestine, conservation in the kidney and storage in the bones.
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    URL: http://dx.doi.org/10.1023/A:1007757321695
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  • 98
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    A simulation model of organic matter and nutrient accumulation in mangrove wetland soils (1999)
    Springer
    Biogeochemistry 44 (1999), S. 93-118 
    Details
    ISSN: 1573-515X
    Keywords: Everglades National Park ; mangrove soils ; organic matter ; nitrogen ; phosphorus ; sedimentation ; simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The distribution and accumulation of organic matter, nitrogen (N) and phosphorus (P) in mangrove soils at four sites along the Shark River estuary of south Florida were investigated with empirical measures and a process-based model. The mangrove nutrient model (NUMAN) was developed from the SEMIDEC marsh organic matter model and parameterized with data from mangrove wetlands. The soil characteristics in the four mangrove sites varied greatly in both concentrations and profiles of soil carbon, N and P. Organic matter decreased from 82% in the upstream locations to 30% in the marine sites. Comparisons of simulated and observed results demonstrated that landscape gradients of soil characteristics along the estuary can be adequately modeled by accounting for plant production, litter decomposition and export, and allochthonous input of mineral sediments. Model sensitivity analyses suggest that root production has a more significant effect on soil composition than litter fall. Model simulations showed that the greatest change in organic matter, N, and P occurred from the soil surface to 5 cm depth. The rapid decomposition of labile organic matter was responsible for this decrease in organic matter. Simulated N mineralization rates decreased quickly with depth, which corresponded with the decrease of labile organic matter. The increase in organic matter content and decrease in soil bulk density from mangrove sites at downstream locations compared to those at upstream locations was controlled mainly by variation in allochthonous inputs of mineral matter at the mouth of the estuary, along with gradients in mangrove root production. Research on allochthonouns sediment input and in situ root production of mangroves is limited compared to their significance to understanding nutrient biogeochemistry of these wetlands. More accurate simulations of temporal patterns of nutrient characteristics with depth will depend on including the effects of disturbance such as hurricanes on sediment redistribution and biomass production.
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    URL: http://dx.doi.org/10.1007/BF00993000
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  • 99
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    Nutrient losses in runoff from grassland and shrubland habitats in Southern New Mexico: I. rainfall simulation experiments (1999)
    Springer
    Biogeochemistry 45 (1999), S. 21-34 
    Details
    ISSN: 1573-515X
    Keywords: Chihuahuan desert ; desert ; desertification ; grassland ; nitrogen ; nutrient budgets ; phosphorus ; runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Rainfall simulation experiments were performed in areas of semiarid grassland (Bouteloua eriopoda) and arid shrubland (Larrea tridentata) in the Chihuahuan desert of New Mexico. The objective was to compare the runoff of nitrogen (N) and phosphorus (P) from these habitats to assess whether losses of soil nutrients are associated with the invasion of grasslands by shrubs. Runoff losses from grass- and shrub-dominated plots were similar, and much less than from bare plots located in the shrubland. Weighted average concentrations of total dissolved N compounds in runoff were greatest in the grassland (1.72 mg/1) and lowest in bare plots in the shrubland (0.55 mg/1). More than half of the N transported in runoff was carried in dissolved organic compounds. In grassland and shrub plots, the total N loss was highly correlated to the total volume of discharge. We estimate that the total annual loss of N in runoff is 0.25 kg/ha/yr in grasslands and 0.43 kg/ha/yr in shrublands — consistent with the depletion of soil N during desertification of these habitats. Losses of P from both habitats were very small.
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    URL: http://dx.doi.org/10.1007/BF00992871
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  • 100
    Electronic Resource
    Electronic Resource
    Nutrient budgets and biogeochemistry in an experimental agricultural watershed in Southeastern China (1999)
    Springer
    Biogeochemistry 45 (1999), S. 1-19 
    Details
    ISSN: 1573-515X
    Keywords: Chaohu Lake ; chemical fertilizer ; cycling ; denitrification ; multipond system ; nitrogen ; nutrient budget ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract During a two-year field study, an annual nutrient budget and cycles were developed for a small agricultural watershed. The study emphasized the integrated unit of the watershed in understanding the biogeochemistry. It was found that the total nutrient input was 39.1× 104 kg nitrogen and 3.91×104 kg phosphorus in the year 1995, of which the greatest input of nutrients to the watershed was chemical fertilizer application, reaching 34.7×104 kg (676 kg/ha) nitrogen and 3.88×104 kg (76 kg/ha) phosphorus. The total nutrient output from the watershed was 13.55×104 kg nitrogen and 0.40×104 kg phosphorus, while the largest output of nitrogen was denitrification, accounting for 44.1% of N output; the largest output of phosphorus was sale of crops, accounting for 99.4% of P output. The results show that the nutrient input is larger than output, demonstrating that there is nutrient surplus within the watershed, a surplus which may become a potential source of nonpoint pollution to area waters. The research showed that both denitrification and volatilization of nitrogen are key ways of nitrogen loss from the watershed. This suggests that careful management of fertilizer application will be important for the sustainable development of agriculture. The research demonstrated that a multipond system within the watershed had high retention rate for both water and nutrients, benefiting the water, nutrient and sediment recycling in the terrestrial ecosystem and helping to reduce agricultural nonpoint pollution at its source. Therefore, this unique watershed system should be recommended due to its great potential relevance for sustainable agricultural development.
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    URL: http://dx.doi.org/10.1007/BF00992870
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