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  • nitrogen  (227)
  • Springer  (227)
  • 1990-1994  (227)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 348-349 
    ISSN: 1573-0972
    Keywords: Aspergillus ; glucoamylase ; nitrogen ; rice bran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Corn steep liquor, peptone or NH inf4 sup+ salts increased the yield of glucoamylase from Aspergillus niger growing in a solid-state fermentation on rice bran up to 360 IU/g dry substrate over 96 h at 30°C.
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  • 2
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    World journal of microbiology and biotechnology 8 (1992), S. 579-584 
    ISSN: 1573-0972
    Keywords: Azolla ; fertilization ; nitrogen ; phosphate ; rice ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Rice performance, in terms of plant height, productive tillering, yield and N-contents of grain and straw, harvest index (grain yield as a percentage of grain plus straw yields) and relative fertilizer N-use efficiency (kg grain yield/kg fertilizer-N) was enhanced by urea, ZnSO4 and green manuring withAzolla caroliniana. Unlike urea fertilizer, calcium superphosphate increased the rate of azolla field colonization and promoted a thick, healthy dark-green mat of the fern. Response to ZnSO4 was higher in the azolla-free sub-subplots. Application of ZnSO4 corrected symptoms of Zn deficiency in rice but the addition of calcium superphosphate in the absence of Zn intensified the symptoms of Zn deficiency.
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  • 3
    ISSN: 1423-0445
    Keywords: carbon/nutrient balance hypothesis ; carbon allocation ; fertilization ; phenolics ; nitrogen ; terpene ; Abies grandis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogen fertilization resulted in a linear increase in the growth ofAbies grandis seedlings, but linear decrease in foliage concentrations of phenolic compounds. These data are consistent with the inverse relationship between growth and production of carbonbased secondary chemicals predicted by the carbon/nutrient balance (CNB) hypothesis. However, in contrast to predictions of the CNB hypothesis, nitrogen fertilization had no effect on foliage terpene concentrations. The results suggest that not all carbon-based chemicals respond in the same manner to environmental variation, and that the carbon/nutrient balance hypothesis does not adequately explain all patterns of environmentally-induced variation in secondary metabolism.
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  • 4
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    Aquatic sciences 56 (1994), S. 16-28 
    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.
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  • 5
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    Aquatic sciences 53 (1991), S. 263-272 
    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.
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  • 6
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    Aquatic sciences 54 (1992), S. 58-76 
    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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  • 7
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    Aquatic sciences 55 (1993), S. 132-142 
    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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  • 8
    ISSN: 1572-9567
    Keywords: Burnett apparatus ; compressibility factor ; density ; ethane ; methane ; mixtures ; nitrogen ; refractive index ; Z-meter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The European Gas Research Group (GERG; Groupe Européen de Recherches Gazières) initiated a round-robin test of six Z-meters manufactured by Desgranges et Huot, a Burnett apparatus, and an interferometric device to back up the pVT data of the Z-meters. Two gas mixtures were measured. One mixture contained 49.7 mol% of methane and 50.3 mol% of nitrogen; the second mixture 81.3 mol% of methane, 16.4 mol% of ethane, and 2.3 mol% of propane. The test temperatures were mainly 280 and 300 K for the first mixture and 290 and 320 K for the second mixture. The maximum pressures were 8 MPa for Z-meters and 12 MPa for the Burnett apparatus and the grating interferometer. The experimental compressibility factors Z of the six Z-meters are generally in agreement within ±0.05%. The agreement with the reference data from the Burnett apparatus and the refractive index measurements is also within ± 0.05%. Only two isotherms of the binary mixtures differ by about 0.1% from the other data. Recent natural gas measurements show substantially the same results.
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  • 9
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    International journal of thermophysics 11 (1990), S. 201-211 
    ISSN: 1572-9567
    Keywords: enthalpy ; heat capacity ; high temperatures ; nitrogen ; virial coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Calculations of the second virial coefficients and their derivatives for the Hulburt-Hirschfelder (HH) and other accurate interaction potentials are used to determine the thermodynamic properties of nitrogen at high temperatures. Unlike the usual methods employing partition functions, which are most accurate at low temperatures where the energy levels are precisely known, the virial coefficient method depends on integrating over potential energy functions which provide a useful description of energies even near the top of the potential well, a region where the vibrational-rotational energy levels are not readily accessible. This makes this method particularly useful for predicting high-temperature properties outside the range of laboratory measurements and beyond the useful limits of the partition function approach. In the present work, we use the virial coefficient method to predict the heat capacities and enthalpies of nitrogen up to 25,000 K.
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  • 10
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    International journal of thermophysics 11 (1990), S. 597-601 
    ISSN: 1572-9567
    Keywords: measurement techniques ; nitrogen ; parallel-plate apparatus ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A parallel-plate apparatus is suited for accurate measurements of the thermal conductivity coefficient of fluids over a wide range of densities. This is illustrated by measurements of the thermal conductivity coefficient of nitrogen at a temperature of 308.15 K and at pressures up to 20.1 MPa with an accuracy of 0.5%. The agreement with a recent correlation based on accurate measurements by other authors is satisfactory.
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  • 11
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    International journal of thermophysics 11 (1990), S. 897-910 
    ISSN: 1572-9567
    Keywords: binary mixtures ; carbon dioxide ; cylindrical resonator ; electrostatic transducers ; ethane ; gas ; isotherm ; methane ; mixtures ; multicomponent ; mixtures ; natural gas ; nitrogen ; propane ; sound speed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A description of a fixed-path length acoustic resonator which uses electrostatic transducers for sound generation and detection is given. Also, a summary of the measurements on 13 binary and 4 multicomponent gas mixtures of natural gas components is given. Data were obtained at pressures to 10 MPa for five isotherms at 25 K increments from 250 to 350 K. The binary mixtures are primarily methane-rich, with either ethane, nitrogen, carbon dioxide, or propane as the second constituent. The multicomponent mixture compositions represent four naturally occurring natural gas mixtures.
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  • 12
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    Nutrient cycling in agroecosystems 37 (1994), S. 93-105 
    ISSN: 1573-0867
    Keywords: Erosion/Productivity Impact Calculator (EPIC) model ; leaching ; lettuce ; net N mineralization ; nitrate ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Low N use efficiency and high nitrate (NO 3 - ) pollution potentials are problems in intensive vegetable production systems. The purpose of this study was to quantify N utilization by lettuce (Lactuca sativa L. cv Salinas), and identify periods of NO 3 - loss in an on-farm study in the Salinas Valley in coastal California. During autumn and winter, surface moisture remained low, and NO 3 - concentrations increased, reflecting high net mineralizable N, as determined by anaerobic incubation, and nitrification potential, as determined by the chlorate inhibition method. At the onset of a large winter storm, tracer levels of15NO 3 - were injected in the top 5 mm of soil in 30 cm-deep cylinders. After two weeks, most of the15N was present as15NO 3 - at 10–30 cm depth. By difference, losses to denitrification accounted for ~ 25% of the surface-applied15N. Leaching below 30 cm did not occur, since no15N enrichment of NO 3 - -N was measured in anion-exchange resin membranes placed at the base of each cylinder. During the crop period, NO 3 - losses were most pronounced after irrigation events. Uptake of N by two crops of lettuce (above- and belowground material) was approximately equal to fertilizer inputs, yet simulation of N fates by the Erosion/Productivity Impact Calculator (EPIC) model indicated losses of 14.6 g-N m−2 by leaching and 2.5 g-N m−2 by denitrification during the 6-month crop period. The large NO 3 - losses can be attributed to accumulation of soil NO 3 - during winter that was leached or denitrified during the irrigated crop period.
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  • 13
    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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  • 14
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    Journal of paleolimnology 4 (1990), S. 1-22 
    ISSN: 1573-0417
    Keywords: sulfate ; carbon ; nitrogen ; hydrogen ; organic matter ; enrichment factor ; lake sediments ; paleolimnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract This paper discusses the use of S as a paleolimnological tracer of limnetic sulfate concentration. A positive relationship (p〈0.05) was found between limnetic sulfate and sediment S concentrations for the Great Lakes, English Lakes, and lakes from the Adirondack and Northern New England regions. There is a positive correlation (p〈0.05) between C and S concentration in sediment across all regions studied. The importance of C in affecting S content in sediment was also examined by a series of cores taken at different water depths in Big Moose Lake (Adirondacks). There was a strong relationship between C and S among cores with sediment from deeper water having higher C and S concentrations (r 2=0.99). Sulfur from the shallower cores had greater concentrations of chromium-reducible S (pyrite), while cores from deeper waters had a greater proportion of organic S fractions including C-bonded S and ester sulfates. For assessing historical changes in S accumulation in sediments, enrichment factors were calculated for the PIRLA lakes. Pre-1900 net sediment accumulation rates of S were very similar across all regions. Sulfur enrichment was greatest in Adirondack sediment which had total post-1900 S accumulation of 1.1 to 7.4 times pre-1900 S accumulation. Sediment from Northern New England (NNE) generally had lower S concentration than Adirondack sediments and S enrichment factors ranged from 1.2 to 2.1. Sediment from the Northern Great Lakes States region had similar S concentration and distribution with depth to NNE sediment. In two Northern Florida lakes, sediment showed little variation in S concentration with depth, but in two other lakes from the same region, there was higher S concentration in deeper layers. Lakes which had the greatest enrichment factors also exhibited the most marked changes in C:S ratios. Ratios of C:N showed little variation (10.6 to 26.1) among the PIRLA lakes. A first order model indicated slow decomposition within these organic rich sediments. Elemental concentrations and ratios of sediment from a variety of lakes and reservoirs were complied. Maximum and minimum elemental ratios for all the data were 28 to 8.1 for C:N, 0.81 to 0.11 for C:H, and 675 to 12.5 for C:S, respectively. For the C:S ratios in all regions except the Great Lakes, the maximum ratio was less than 231. Both the maximum and minimum amount of N and H concentration of organic matter is related to biotic processes. The minimum concentration of S is regulated not only by nutrient demands but also by non-assimilatory processes. Sulfur incorporation into sediments is a function of a complex of factors, but limnetic sulfate concentration and organic matter content play a major role in regulating the S content of sediment. Further quantification of S incorporation pathways will aid in the paleolimnological interpretation of sediment S profiles. Such information is also important in assessing how S sediment pools will respond to decreases in limnetic sulfate concentration which may occur with decreases in inputs from acidic deposition.
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  • 15
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    Nutrient cycling in agroecosystems 40 (1994), S. 105-108 
    ISSN: 1573-0867
    Keywords: annual ryegrass ; dry matter ; logistic ; model ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The logistic model has proven very useful in relating dry matter production of warm season perennial forage grasses to applied nitrogen. A recent extension of the model coupled dry matter and plant N accumulation through a common response coefficient c. The objective of this analysis was to apply the extended logistic model to cool season Gulf annual ryegrass (Lolium multiflorum Lam.) and to establish a common response coefficient c between accumulation of dry matter and plant N. Analysis of variance established the validity of this hypothesis. The model accurately described response of dry matter, plant N removal, and plant N concentration to applied N, with an overall correlation coefficient of 0.9954. Furthermore, the model closely described the relationship between yield and plant N removal, as well as between plant N concentration and plant N removal. The logistic equation is well-behaved and simple to use on a pocket calculator. It can be used to estimate yields and plant N removal in evaluation of agricultural production and environmental quality.
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  • 16
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    Nutrient cycling in agroecosystems 40 (1994), S. 165-173 
    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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  • 17
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    Nutrient cycling in agroecosystems 37 (1994), S. 227-234 
    ISSN: 1573-0867
    Keywords: catch crop ; mineralization ; nitrogen ; plant species ; residual effects ; soil depletion ; winter hardiness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ten widely different plant species were compared for their ability to reduce soil mineral nitrogen levels in the autumn and their ability to improve the nitrogen nutrition of the succeeding crop. The species included monocots and dicots, crops that survived the winter (persistent) or were winter killed (non-persistent) as well as legumes and non legumes. Their ability to reduce soil mineral nitrogen content was dependent on both root depth and persistency of the crops in the autumn. For non-persistent catch crops most of the mineralization of plant nitrogen occurred during the winter, and for some of these so early as to allow leaching of some mineralized nitrogen. For persistent crops most of the mineralization occurred shortly after incorporation in the spring. The effect of the catch crops on nitrogen uptake by the succeeding barley crop varied from 13 to 66 kg N ha−1 and the differences between the crops could not be related to any single character, but to a combination of root depth, persistency, plant nitrate accumulation, and depletion of the soil mineral nitrogen pool in spring.
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  • 18
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    Entomologia experimentalis et applicata 64 (1992), S. 225-238 
    ISSN: 1570-7458
    Keywords: Lymantria dispar (L.) ; diet switching ; nitrogen ; specialization ; plant-animal interactions ; insect behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gypsy moth (Lymantria dispar (L.) (Lepidoptera: Lymantriidae)) larvae were reared from hatch on 1.25% N or 3.5% N artificial diet (previous diet) and switched reciprocally to the other diet (current diet) after molting into the second, third, fourth, or fifth instar. The nitrogen concentration of food consumed during previous instars had a strong residual effect on the growth rate in subsequent instars when a diet switch was made during instars two through four, but did not affect growth rate of fifth-instar larvae despite effects on food consumption and utilization. In early instars, larvae reared on 1.25% N artificial diet and then switched to 3.75% N diet had lower mass-adjusted growth rates than larvae continuously reared on 3.75% N diet. Conversely, larvae reared on 3.75% N diet and switched to 1.25% N had higher mass-adjusted growth rates than larvae reared continuously on 1.25% N diet. Relative to larvae previously reared on 1.25% N diet, fifth-instar male larvae previously reared on 3.75% N diet had slightly lower consumption rates, higher net growth efficiency (ECD), and higher gross growth efficiency (ECI). Larvae previously reared on 3.75% N diet tended to have lower food assimilation efficiency (AD) and lower nitrogen assimilation efficiency (AD(N)). Although both previous and current diet nitrogen concentration strongly affected larval growth and food utilization, the interaction term between these was not significant for any response variables except ECD and ECI. Because the interaction term reflects the effect of switching per se, the results indicate that there was a metabolic cost associated with switching, but no inherent net cost or benefit of diet-switching to growth.
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  • 19
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    Catalysis letters 13 (1992), S. 45-53 
    ISSN: 1572-879X
    Keywords: Ammonia ; synthesis ; nitrogen ; rate-determining step ; potassium promotion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The simple concept of a single rate-determining step, the dissociation of N2(a), in ammonia synthesis is inconsistent with experimental results. It is proposed that three reaction steps, N2(a) → 2N(a) (1) N(a) + H(a)→NH(a) (2) NH3(a)→NH3(g) (3) are dominant in determining the rate of synthesis. Under industrial conditions reactions (2) and (3) are more important than (1). The role of K+ as promoter in these reactions is discussed, especially as an “anchor” for adsorbed oxygen.
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  • 20
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    Catalysis letters 16 (1992), S. 159-164 
    ISSN: 1572-879X
    Keywords: Chemisorption ; nitrogen ; carbon dioxide ; platinum ; water gas shift reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The relationship between sites responsible for nitrogen chemisorption and sites responsible for stronger adsorption of carbon dioxide on platinum black is reported. A 2 to 1 ratio has been found between molecules of more strongly adsorbed carbon dioxide and molecules of nitrogen chemisorbed on individual samples. This relationship has allowed us to deduce the structure of chemisorbed carbon dioxide. Carbon dioxide is relatively weakly chemisorbed on platinum. Reasons for the weakness of this chemisorption are discussed.
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  • 21
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    Biogeochemistry 9 (1990), S. 117-134 
    ISSN: 1573-515X
    Keywords: nitrogen ; Mediterranean ; natural versus anthropogenic atmospheric nitrogen ; atmospheric input ; riverine input ; marine ecosystems ; primary production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Bulk inorganic nitrogen deposition was monitored over a period of 3 years at the Bavella Pass (Corsica, France). Annual fluxes range between 126 and 150μmol.m−2.d-−1, increasing slightly with annual rainfall. Natural background average concentrations of rain water and associated fluxes were estimated from a classification of rain events into ‘natural’ (Oceanic and Saharan), polluted and composite. Long range transport of incoming polluted air masses increases the atmospheric wet nitrogen input by at least a factor of 1.6 in this Mediterranean area. Extrapolation of atmospheric dissolved inorganic nitrogen input to the Western Mediterranean leads to fluxes of 80 to l00μmol.m−2.d-−1. This atmospheric input is in the same order of magnitude as the inorganic nitrogen riverine input. As a consequence, the nitrogen budget for the Mediterranean has had to be reassessed. Atmospheric wet inorganic nitrogen input is of noticeable importance to marine Mediterranean ecosystems, representing on average 10 to 25% of new production in the Western Basin, with values of up to 60% in oligotrophic zones.
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  • 22
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    Biogeochemistry 10 (1990), S. 1-28 
    ISSN: 1573-515X
    Keywords: boreal forest ; decomposition ; litter quality ; nitrogen ; productivity ; soil temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A model of boreal forest dynamics was adapted to examine the factors controlling carbon and nitrogen cycling in the boreal forests of interior Alaska. Empirical relationships were used to simulate decomposition and nitrogen availability as a function of either substrate quality, the soil thermal regime, or their interactive effects. Test comparisons included black spruce forests growing on permafrost soils and black spruce, birch, and white spruce forests growing on permafrost-free soils. For each forest, simulated above-ground tree biomass, basal area, density, litterfall, moss biomass, and forest floor mass, turnover, thickness, and nitrogen concentration were compared to observed data. No one decay equation simulated forests entirely consistent with observed data, but over the range of upland forest types in interior Alaska, the equation that combined the effects of litter quality and the soil thermal regime simulated forests that were most consistent with observed data. For black spruce growing on permafrost soils, long-term simulated forest dynamics in the absence of fire resulted in unproductive forests with a thick forest floor and low nitrogen mineralization. Fires were an important means to interrupt this sequence and to restart forest succession.
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  • 23
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    Biogeochemistry 12 (1991), S. 129-134 
    ISSN: 1573-515X
    Keywords: biomass burning ; forest soils ; nitrogen ; sulphur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The proportion of total sulphur lost during combustion (600 °C) of Douglas-fir (Pseudotsuga menziesii) foliage is reduced from〉 90% to 65–70% as the SO4-S concentration increases from 10% to 45–50% of the total S content. Foliar SO4-S content is decreased by improvement of plant nitrogen status, suggesting that alterations to soil N availability may influence S transfer to the atmosphere during biomass burning.
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  • 24
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    Biogeochemistry 15 (1991), S. 21-46 
    ISSN: 1573-515X
    Keywords: denitrification ; forest ; nitrification ; nitrogen ; nitrogen mineralization ; N20 ; proton budget ; The Netherlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Within a long-term research project studying the biogeochemical budget of an oak-beech forest ecosystem in the eastern part of the Netherlands, the nitrogen transformations and solute fluxes were determined in order to trace the fate of atmospherically deposited NH4 + and to determine the contribution of nitrogen transformations to soil acidification. The oak-beech forest studied received an annual input of nitrogen via throughfall and stemflow of 45 kg N ha−1 yr−1, mainly as NH4 +, whereas 8 kg N ha−1 yr−1 was taken up by the canopy. Due to the specific hydrological regime resulting in periodically occurring high groundwater levels, denitrification was found to be the dominant output flux (35 kg N ha−1 yr−1). N20 emmission rate measurements indicated that 57% of this gaseous nitrogen loss (20 kg N ha−1 yr−1) was as N2O. The forest lost an annual amount of 11 kg N ha−1 yr−1 via streamwater output, mainly as N03 −. Despite the acid conditions, high nitrification rates were measured. Nitrification occurred mainly in the litter layer and in the organic rich part of the mineral soil and was found to be closely correlated with soil temperature. The large amount of NH4 + deposited on the forest floor via atmospheric deposition and produced by mineralization was to a large extent nitrified in the litter layer. Almost no NH4 + reached the subsurface soil horizons. The N03 − was retained, taken up or transformed mainly in the mineral soil. A small amount of N03 − (9 kg N ha−1 yr−1) was removed from the system in streamwater output. A relatively small amount of nitrogen was measured in the soil water as Dissolved Organic Nitrogen. On the basis of these data the proton budget of the system was calculated using two different approaches. In both cases net proton production rates were high in the vegetation and in the litter layer of the forest ecosystem. Nitrogen transformations induced a net proton production rate of 2.4 kmol ha−1 yr−1 in the soil compartment.
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    Biogeochemistry 10 (1990), S. 67-79 
    ISSN: 1573-515X
    Keywords: deserts ; ecosystem ; nitrogen ; nutrient cycling ; soils ; southwestern United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A lower limit for nitrogen loss from desert ecosystems in the southwestern United States was estimated by comparing nitrogen inputs to the amount of nitrogen stored in desert soils and vegetation. Atmospheric input of nitrogen for the last 10 000 years was conservatively estimated to be 2.99 kg N/m2. The amount of nitrogen stored in desert soils was calculated to be 0.604 kg N/m3 using extant data from 212 profiles located in Arizona, California, Nevada, and Utah. The average amount of nitrogen stored in desert vegetation is approximately 0.036 kg N/m2. Desert conditions have existed in the southwestern United States throughout the last 10 000 years. Under such conditions, vertical leaching of nitrogen below a depth of 1 m is small (ca. 0.028 kg N/m2 over 10 000 years) and streamflow losses of nitrogen from the desert landscape are negligible. Thus, the discrepancy found between nitrogen input and storage represents the amount of nitrogen lost to the atmosphere during the last 10 000 years. Loss of nitrogen to the atmosphere was calculated to be 2.32 kg N/m2, which is 77% of the atmospheric inputs. Processes resulting in nitrogen loss to the atmosphere from desert ecosystems include wind erosion, ammonia volatilization, nitrification, and denitrification. Our analysis cannot assess the relative importance of these processes, but each is worthy of future research efforts.
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  • 26
    ISSN: 1573-515X
    Keywords: cumulative ; flow ; GIS ; landscape ; lead ; nitrogen ; phosphorus ; suspended solids ; watershed ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A method was developed to evaluate the cumulative effect of wetland mosaics in the landscape on stream water quality and quantity in the nine-county region surrounding Minneapolis—St. Paul, Minnesota. A Geographic Information System (GIS) was used to record and measure 33 watershed variables derived from historical aerial photos. These watershed variables were then reduced to eight principal components which explained 86% of the variance. Relationships between stream water quality variables and the three wetland-related principal components were explored through stepwise multiple regression analysis. The proximity of wetlands to the sampling station was related to principal component two, which was associated with decreased annual concentrations of inorganic suspended solids, fecal coliform, nitrates, specific conductivity, flow-weighted NH4 flow-weighted total P, and a decreased proportion of phosphorus in dissolved form(p 〈 0.05). Wetland extent was related to decreased specific conductivity, chloride, and lead concentrations. The wetland-related principal components were also associated with the seasonal export of organic matter, organic nitrogen, and orthophosphate. Relationships between water quality and wetlands components were different for time-weighted averages as compared to flow-weighted averages. This suggests that wetlands were more effective in removing suspended solids, total phosphorus, and ammonia during high flow periods but were more effective in removing nitrates during low flow periods.
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  • 27
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    Biogeochemistry 12 (1991), S. 135-148 
    ISSN: 1573-515X
    Keywords: fens ; management ; nitrogen ; phosphorus ; productivity ; vegetation ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A fertilization experiment was carried out in 3 mesotrophic fens to investigate whether plant growth in these systems is controlled by the availability of N, P or K. The fens are located in an area with high N inputs from precipitation. They are annually mown in the summer to prevent succession to woodland. Above-ground plant biomass increased significantly upon N fertilization in the two “mid”-succession fens studied. In the “late”-succession fen that had been mown for at least 60 years, however, plant biomass increased significantly upon P fertilization. The mowing regime depletes the P pool in the soil, while it keeps N inputs and outputs in balance. A long-term shift occurs from limitation of plant production by N toward limitation by P. Hence, mowing is a suitable management tool to conserve the mesothrophic character of the fens.
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  • 28
    ISSN: 1573-515X
    Keywords: atmospheric deposition ; nitrogen ; nutrient cycling ; spruce decline ; subalpine spruce-fir
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    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nitrogen inputs, fluxes, internal generation and consumption, and outputs were monitored in a subalpine spruce-fir forest at approximately 1000-m elevation on Whiteface Mountain in the Adirondacks of New York, USA. Nitrogen in precipitation, cloudwater and dry deposition was collected on an event basis and quantified as an input. Throughfall, stemflow, litterfall and soil water were measured to determine fluxes within the forest. Nitrogen mineralization in the forest floor was estimated to determine internal sources of available N. Lower mineral horizon soil water was used to estimate output from the ecosystem. Vegetation and soil N pools were determined. During four years of continuous monitoring, an average of 16 kg N ha−1 yr−1 was delivered to the forest canopy as precipitation, cloudwater and dry deposition from the atmosphere. Approximately 30% of the input was retained by the canopy. Canopy retention is likely the result of both foliar uptake and immobilization by bark, foliage and microorganisms. Approximately 40 kg of N was made available within the forest floor from mineralization of organic matter. Virtually all the available ammonium (mineralized plus input from throughfall) is utilized in the forest floor, either by microorganisms or through uptake by vegetation. The most abundant N component of soil water solutions leaving the system was nitrate. Net ecosystem fluxes indicate accumulation of both ammonium and nitrate. There is a small net loss of organic N from the ecosystem. Some nitrate leaves the bottom of the B horizon throughout the year. Comparisons with other temperate coniferous sites and examination of the ecosystem N mass balance indicate that N use efficiency is less at our site, which suggests that the site is not severely limited by N.
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  • 29
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    Biogeochemistry 18 (1992), S. 1-17 
    ISSN: 1573-515X
    Keywords: microbial biomass-N ; desert ; carbon ; nitrogen ; shrubland ; grassland ; playa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Microbial biomass nitrogen was measured in unamended (dry) and wetted soils in ten shrubland and grassland communities of the Chihuahuan desert, southern New Mexico, by the fumigation-extraction method. Microbial biomass-N in dry soils was undetectable. Average microbial biomass-N in wetted soils among all plant communities was 15.3 μg g-1 soil. Highest values were found in the communities with the lowest topographic positions, and the minimum values were detected in the spaces between shrubs. Microbial biomass was positively and significantly correlated to soil organic carbon and extractable nitrogen (NH4 + + NO3 -). In a stepwise multiple regression, organic carbon and extractable nitrogen accounted for 40.9 and 5.6%, respectively, of the variance in microbial biomass-N among all the samples. Among communities, the soil microbial biomass was affected by the ratio of carbon to extractable nitrogen. Our results suggest a succession in the control of microbial biomass from nitrogen to carbon when the ratio of carbon to nitrogen decreases during desertification.
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    Biogeochemistry 18 (1992), S. 19-35 
    ISSN: 1573-515X
    Keywords: Dinitrogen fixation ; nitrogen ; phosphorus ; competition ; legumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract An analysis of data compiled from the literature confirms a strong inverse relationship between annual rates of nitrogen fixation and the soil nitrogen content in agricultural and pastoral ecosystems. However, this inverse relationship is strongly modified by the rate of application of phosphorus fertilizer, which strongly influences the activities of both symbiotic and non-symbiotic nitrogen fixing organisms. In the case of symbiotic legumes, the response of N-fixation to N and P is in part a result of changes in legume dominance within the plant community. These results, as well as supporting data presented from a review of experiments on nitrogen fixation in a variety of other terrestrial and aquatic ecosystems, provide important support for the hypothesis that phosphorus availability is a key regulator of nitrogen biogeochemistry.
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    Biogeochemistry 22 (1993), S. 157-178 
    ISSN: 1573-515X
    Keywords: Serengeti ; productivity ; precipitation ; nitrogen ; grazing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract In the Serengeti National Park, Tanzania, precipitation and soil nitrogen vary greatly between northwestern tallgrass areas and southeastern shortgrass areas, with the tallgrass having higher total precipitation and lower soil fertility. We used a model of grassland productivity, carbon/nitrogen cycling, and abiotic factors to test the hypothesis that tallgrass productivity is limited primarily by nitrogen availability while shortgrass productivity is limited by water. Under observed grazing intensities and ungrazed conditions, precipitation exerted primary control over grassland productivity for both regions, with differences in soil texture mediating soil water availability to the grasses. Mineral nitrogen availability interacted with water availability to influence productivity at precipitation levels ⩾ 130% of the mean. Nitrogen mineralization and precipitation were positively related for each grassland type, however, nitrification varied both between grassland types and between grazed and ungrazed conditions. Combined mineralization and nitrification could not maintain soil mineral nitrogen levels in the face of plant nitrogen uptake stimulated by increased precipitation, thus providing the mechanism by which nitrogen becomes a secondary limiting factor for both grasslands. Model experiments indicated that the pattern of primary limitation by precipitation and secondary limitation by nitrogen was robust to model assumptions concerning ungulate deposition of urine and dung nitrogen to the soil.
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    Biogeochemistry 25 (1994), S. 19-39 
    ISSN: 1573-515X
    Keywords: denitrification ; mineralization ; nitrification ; nitrogen ; riparian ; stream ; wetland ; New Jersey ; Pennsylvania ; Pinelands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Denitrification (N2 production) and oxygen consumption rates were measured at ambient field nitrate concentrations during summer in sediments from eight wetlands (mixed hardwood swamps, cedar swamps, heath dominated shrub wetland, herbaceous peatland, and a wetland lacking live vegetation) and two streams. The study sites included wetlands in undisturbed watersheds and in watersheds with considerable agricultural and/or sewage treatment effluent input. Denitrification rates measured in intact cores of water-saturated sediment ranged from ≤ 20 to 260 μmol N m-2 h-1 among the three undisturbed wetlands and were less variable (180 to 260 μmol N M-2 h-1) among the four disturbed wetlands. Denitrification rates increased when nitrate concentrations in the overlying water were increased experimentally (1 up to 770 μM), indicating that nitrate was an important factor controlling denitrification rates. However, rates of nitrate uptake from the overlying water were not a good predictor of denitrification rates because nitrification in the sediments also supplied nitrate for denitrification. Regardless of the dominant vegetation, pH, or degree of disturbance, denitrification rates were best correlated with sediment oxygen consumption rates (r 2 = 0.912) indicating a relationship between denitrification and organic matter mineralization and/or sediment nitrification rates. Rates of denitrification in the wetland sediments were similar to those in adjacent stream sediments. Rates of denitrification in these wetlands were within the range of rates previously reported for water-saturated wetland sediments and flooded soils using whole core15N techniques that quantify coupled nitrification/denitrification, and were higher than rates reported from aerobic (non-saturated) wetland sediments using acetylene block methods.
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  • 33
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    Biogeochemistry 11 (1990), S. 1-22 
    ISSN: 1573-515X
    Keywords: disturbance ; ecosystems ; forests ; indirect interactions ; landscape ecology ; Minnesota ; nitrogen ; nutrient cycling ; path analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Path analysis was used to determine the importance of long-term disturbance regime and the relative importances of correlations among vegetation patterns, disturbance history, and nitrogen (N) mineralization in old-growth forests of northwestern Minnesota. Leaf biomass (estimated by allometric equations), fire history (from fire scars on Pinus resinosa trees), and N mineralization rates (estimated from incubationsin situ) were determined from sample plots dominated by Betula papyrifera, Populus tremuloides, andP. grandidentata a mixture ofAcer saccharumandTilia americana, or Quercus borealis andOstrya virginiana. Results showed that topographic and soil-moisture controls on N mineralization, vegetation patterns, and disturbance are substantially stronger than is suggested by direct correlation. Indirect interactions among ecosystem variables played in important role. These interactions probably include the tendency for species that cycle large amounts of N to colonize more mesic sites that burned rarely in the past. Soil moisture was correlated both directly with N mineralization and indirectly, through its effects on vegetation pattern, and thus, litter quality. Although disturbance regime also depended on topography, the strengths of relationships between disturbance regime and other variables were relatively weak. These dependencies suggested that long-term fire regime is probably more a consequence than a cause for vegetation and fertility patterns. Topography, through its effects on soil moisture and microclimate, is an overriding influence on ecosystem properties, which in turn influence fire regime.
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  • 34
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    Biogeochemistry 11 (1990), S. 23-43 
    ISSN: 1573-515X
    Keywords: acid precipitation ; ammonium ; mass balance ; nitrate ; nitrogen ; retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The relative contribution of HN03 to precipitation acidity in eastern Canada has increased in recent years leading to some concern that the relative importance of NO− 3 deposition in acidification of terrestrial and aquatic ecosystems may increase. To gauge the extent of this impact, annual mass balances for N0− 3 and NH+ 4 were calculated for several forested catchments and lakes in Ontario. Retention of NH+ 4 (R NH4) by forested catchments was consistently high compared to retention of NO3 − (R NO3) which was highly variable. Retention of inorganic nitrogen was influenced by catchment grade and areal water discharge. In lakes, the reciprocals of retention of N0− 3 and NH+ 4 were linearly related to the ratio of lake mean depth to water residence time (z/τ; equal to areal water discharge), and retention did not appear to be a function of degree of acidification of the lakes. Net N consumption-based acidification of lakes, defined as the ratio of annual NH; mass to N0− 3 mass consumption, was negatively correlated with /τ and N consumption-related acidification was most likely to occur when − was 〈 1.5 m yr−1. If retention mechanisms are unaffected by changes in deposition, changes in deposition will still result in changes in surface water concentrations although the changes will be of similar proportions. Therefore, ‘NO− 3 saturation’ should not be defined by concentrations alone, but should be defined as decreasing long-term, average NO− 3 retention in streams and lakes in response to long-term increases in NO− 3 deposition. Analysis o f survey data will be facilitated by grouping lakes and catchments according to similar characteristics.
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  • 35
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    Biogeochemistry 15 (1992), S. 213-228 
    ISSN: 1573-515X
    Keywords: immobilization ; leaf litter decomposition ; lignin ; Mediterranean ecosystem ; nitrogen ; tannin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Nitrogen immobilization in relation to the dynamics of lignin and tannins in nine different types of leaf litter was investigated during a 2-yr study at two Mediterranean ecosystems of SW Spain. Net nitrogen immobilization for all the species was higher in a forest than in the more nutrient-poor soil of a shrubland. Absolute amount of lignin increased in both ecosystems in the first 2–4 months whereas tannin rapidly decreased in the same time period. Increases in lignin were significantly correlated to losses of tannins during decomposition. Initial tannin content was the best predictor of the maximum amount of immobilized nitrogen in litter in both ecosystems. Mechanisms that could explain the immobilization of nitrogen in litter are discussed.
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  • 36
    ISSN: 1573-515X
    Keywords: N2O ; CH4 ; red spruce ; balsam fir ; spruce-fir ; forests ; nitrogen ; deposition ; nitrification ; mineralization ; denitrification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We measured the exchange of N2O and CH4 between the atmosphere and soils in 5 spruce-fir stands located along a transect from New York to Maine. Nitrous oxide emissions averaged over the 1990 growing season (May–September) ranged from 2.1 ug N2O-N/m2-hr in New York to 0.4 ug N2O-N/m2-hr in Maine. The westernmost sites, Whiteface Mtn., New York and Mt. Mansfield, Vermont, had the highest nitrogen-deposition, net nitrification and N2O emissions. Soils at all sites were net sinks for atmospheric CH4 Methane uptake averaged over the 1990 growing season ranged from 0.02 mg CH4-C/M2-hr in Maine to 0.05 mg CH4-C/m2-hr in Vermont. Regional differences in CH4 uptake could not be explained by differences in nitrogen-deposition, soil nitrogen dynamics, soil moisture or soil temperature. We estimate that soils in spruce-fir forests at our study sites released ca. 0.02 to 0.08 kg N2O-N/ha and consumed ca. 0.74 to 1.85 kg CH4 C/ha in the 1990 growing season.
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  • 37
    ISSN: 1573-515X
    Keywords: nitrogen ; phosphorus ; soil fertility ; tropical forest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We measured concentrations of soil nutrients (0–15 and 30–35 cm depths) before and after the dry season in control and dry-season irrigated plots of mature tropical moist forest on Barro Colorado Island (BCI) in central Panama to determine how soil moisture affects availability of plant nutrients. Dry-season irrigation (January through April in 1986, 1987, and 1988) enhanced gravimetric soil water contents to wet-season levels (ca. 400 g kg−1 but did not cause leaching beyond 0.8 m depth in the soil. Irrigation increased concentrations of exchangeable base cations (Ca2+, Mg2+, K+, Na+), but it had little effect on concentrations of inorganic N (NH4 +C, NO3 − and S (SO4 2−). These BCI soils had particularly low concentrations of extractable P especially at the end of the dry season in April, and concentrations increased in response to irrigation and the onset of the rainy season. We also measured the response of soil processes (nitrification and S mineralization) to irrigation and found that they responded positively to increased soil moisture in laboratory incubations, but irrigation had little effect on rates in the field. Other processes (plant uptake, soil organic matter dynamics) must compensate in the field and keep soil nutrient concentrations at relatively low levels.
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  • 38
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    Biogeochemistry 20 (1993), S. 45-62 
    ISSN: 1573-515X
    Keywords: atmospheric deposition ; forest ecosystems ; litter decomposition ; The Netherlands ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Litterbag experiments were carried out in five forest ecosystems in the Netherlands to study weight loss and nitrogen dynamics during the first two years of decomposition of leaf and needle litter. All forests were characterized by a relatively high atmospheric nitrogen input by throughfall, ranging from 22–55 kg N ha−1 yr−1. Correlation analysis of all seven leaf and needle litters revealed no significant relation between the measured litter quality indices (nitrogen and lignin concentration, lignin-to-nitrogen ratio) and the decomposition rate. A significant linear relation was found between initial lignin-to-nitrogen ratio and critical nitrogen concentration, suggesting an effect of litter quality on nitrogen dynamics. Comparison of the decomposition of oak leaves in a nitrogen-limited and a nitrogen-saturated forest suggested an increased nitrogen availability. The differences in capacities to retain atmospheric nitrogen inputs between these two sites could be explained by differences in net nitrogen immobilization in first year decomposing oak leaves: in the nitrogen-limited oak forest a major part (55%) of the nitrogen input by throughfall was immobilized in the first year oak leaf litter. The three coniferous forests consisted of two monocultures of Douglas fir and a mixed stand of Douglas fir and Scots pine. Despite comparable litter quality in the Douglas fir needles in all sites, completely different nitrogen dynamics were found.
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  • 39
    ISSN: 1573-5060
    Keywords: Wheat ; Triticum aestivum ; landrace ; semidwarf ; phosphorus ; nitrogen ; fertilization ; genetic improvement ; breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In recent decades, most winter wheat (Triticum aestivum L.) breeding in the United States has been done in field nurseries in which the soil receives ample fertilization. To determine the effects of these breeding efforts on productivity under low-fertility conditions, we evaluated twenty-nine winter wheat genotypes (seven Asian landraces; thirteen standard-height U.S. cultivars released between 1874 and 1971; and nine semidwarf cultivars released between 1977 and 1988) under severe fertility stress at three Kansas, USA locations. Experiments included fertilized and unfertilized treatments. The modern, semidwarf cultivars yielded 18% and 20% more, on average, than landraces and standard-height cultivars under low and high fertility, respectively; however, only the latter difference reached the 5% significance level. At only one location (Hays) was there a significant genotype X fertility interaction: there, 89% of the semidwarf cultivars, only 8% of the standard cultivars, and 57% of the landraces responded to fertilization. The regression coefficient of mean grain yield (unfertilized) on year of introduction or release for standard and semidwarf cultivars was zero, indicating that a century of breeding has produced no genetic improvement in performance under these low-fertility conditions. Although we found that the usual yield advantage of modern cultivars is not expressed under very low fertility, we saw no evidence that older cultivars are superior under those conditions.
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  • 40
    ISSN: 1573-5095
    Keywords: eucalypt ; regrowth forest ; litter ; litterfall ; fertilizer ; nitrogen ; nutrient cycling ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of fertilizer treatment on nutrient transfers to the forest floor were examined in regrowth Eucalyptus diversicolor F. Muell. forest. Dry weight and nutrient content of leaf litterfall and total litterfall were measured for 3 years in a stand to which two levels of N (0, 200 kg ha-1 year-1) were applied each year at each of three levels of a single initial application of P (0, 30, 200 kg ha-1). Annual accessions of litter to the forest floor were significantly increased by additions of both N (by 17%, 18% and 21% in the 3 years) and 200 kg P ha-1 (by 8%, 8% and 4% in the 3 years) but there was no interaction between effects of N and P treatments. Fertilizer application also had a significant effect on the nutrient content of leaf litterfall and total litterfall. Concentration of N in leaf litterfall was 9% to 23% greater on plots treated with N fertilizer compared to untreated plots. The amounts of N in litterfall were about 30% greater on N-treated compared to untreated plots. On plots treated with 200 kg P ha-1, P concentrations in leaf litter were 50% to 100% greater than in litter from plots receiving no P. Application of 200 kg P ha-1 increased the amounts of P in annual litterfall by 32% to 87%. The greatest increase in P accessions occurred soon after fertilizer treatment. The amounts of Ca, K, and Na in litterfall were also significantly increased by fertilizer application. For Ca and K this was due partly to increases in element concentrations in litterfall following application of treatments. The effect of fertilizers on internal recycling of plant nutrients and on litter accumulation and nutrient dynamics in forest floor litter is discussed.
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  • 41
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    Journal of aquatic ecosystem stress and recovery 3 (1994), S. 27-34 
    ISSN: 1573-5141
    Keywords: nutrient limitation ; critical tissue concentrations ; nitrogen ; phosphorus ; macroalgae ; biomonitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Discs of the macroalga,Ulva lactuca L., were transplanted around an ocean outfall and at a reference site in Køge Bay, Denmark, to assess the influence of the outfall on the nutrient availability. At 2-wk intervals, samples were collected and analyzed for growth, nitrogen, and phosphorus content. The tissue concentrations of nitrogen and phosphorus decreased with distance to the outfall, showing that the tissue concentrations are suitable for monitoring nutrient availability in coastal areas and provide a time-integrated measure of the nutrient availability. The lowest tissue concentrations of nitrogen were recorded at the reference station, where the internal concentrations generally were below the critical concentration level, showing that nitrogen limited the growth. At the station located close to the outfall, the flux of nitrogen was sufficient to maintain the maximum growth rate. The tissue concentrations of phosphorus were only below the critical concentration level on one occasion, and the result showed a net uptake throughout the study period. It was concluded that in the Køge Bay, nitrogen was the main limiting factor for macroalgae growth during the summer. The applicability of tissue concentrations for assessment of nutrient availability is discussed and it is considered that the method, when evaluated against established critical concentrations, provides a valuable tool for assessing ecosystem health with regard to eutrophication.
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  • 42
    ISSN: 1573-515X
    Keywords: nitrogen ; snow ; flux
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    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Increased emissions of nitrogen compounds to the atmosphere by human activities have been well documented. However, in order to better quantify these anthropogenic emissions, better knowledge of natural emissions rates must be known. In addition, variation in natural emissions through time should be documented. In this note we present data collected and/or analyzed by us for NO3 − in recent snow from remote regions of the world. We also summarize existing data sets from other remote regions. This is done to establish a better understanding of NO3 − deposition rates in these regions as well as to add more information to our global understanding of NO3 − deposition.
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  • 43
    ISSN: 1573-515X
    Keywords: algae ; nitrogen ; nutrient ; phosphorus ; regeneration ; zooplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Most ecosystem models consolidate members of food-webs, e.g. species, into a small number of functional components. Each of these is then described by a single state variable such as biomass. When a multivariate approach incorporating multiple substances within components is substituted for this univariate one, a ‘stoichiometric’ model is formed. Here we show that the Nitrogen:Phosphorus ratio within zooplankton herbivores varies substantially intraspecifically but not intraspecifically. By using stoichiometric theory and recent measurements of the N:P ratio within different zooplankton taxa, we calculate large differences in ratios of nutrients recycled by different zooplankton species. Finally, we demonstrate that N:P stoichiometry can successfully account for shifts in N- and P-limitation previously observed in whole-lake experiments. Species stoichiometry merges food-web dynamics with biogeochemical cycles to yield new insights.
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  • 44
    ISSN: 1573-515X
    Keywords: chronosequence ; montane tropical forest ; nitrogen ; soil development ; phosphorus ; tropical forest
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    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We determined the effects of nutrient amendments on plant growth in three tropical montane rainforest sites representing a sequence of soil ages (〈 30, 200, and ≈ 2000 y). Factorial fertilization with nitrogen, phosphorus, and all other essential nutrients (combined) was applied to the two younger sites; only nitrogen was applied to the oldest one. Nitrogen supply represented the most important limitation to plant growth in the two younger sites; additions of nitrogen caused significant increases in tree diameter increment, height growth, litterfall, and most other growth-related parameters. In contrast, nitrogen additions had no significant effect on plant growth in the oldest site. Phosphorus additions increased extractable soil phosphorus and plant tissue phosphorus, but did not increase plant growth at the young sites. The results are consistent with Walker & Syers' (1976) model for the control of nutrient limitation during soil development.
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    Entomologia experimentalis et applicata 61 (1991), S. 7-16 
    ISSN: 1570-7458
    Keywords: Plutella xylostella ; Trichoplusia ni ; Hellula phidilealis ; Artogeia rapae ; nitrogen ; population growth ; cabbage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of different nitrogen (N) fertilization rates (0, 45, 90, and 168 kg N/ha), plant nitrogen concentration, and plant biomass on abundance and population growth of diamondback moth, Plutella xylostella (L.), cabbage looper, Trichoplusia ni (Hübner), cabbage budworm, Hellula phidilealis (Walker), imported cabbageworm, Artogeia rapae (L.), and cross-striped cabbageworm, Evergestis rimosalis (Guenée), were investigated in Homestead and Sanford, Florida in 1987. The effects of these factors on the parasitization of P. xylostella were also examined. In Homestead, abundance of most insect pests and parasitized P. xylostella increased with an increase in the level of N applied and with an increase in plant biomass. Similar results were found in Sanford, although results were not consistently significant. Abundance of most insect pests was significantly positively correlated with plant N concentration. Multiple regression analyses indicated that foliar biomass was significantly more important than N fertilization rate and subsequent plant N concentration at predicting abundance of insect pests and parasitized P. xylostella on cabbage.
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  • 46
    ISSN: 1572-9680
    Keywords: alley cropping ; maize ; nitrogen ; organic matter ; soil fertility ; Leucaena leucocephala ; Flemingia congesta
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A detailed study of the soil chemical and physical properties in seven-year-old alley cropping trial containingLeucaena leucocephala andFlemingia congesta in Northern Zambia is described. There was a strong correlation between the maize yield and the total amount of nitrogen applied, both from prunings and fertiliser, suggesting that a major reason for the observed benefit from alley cropping, particularly withLeucaena, was due to an improvement in nitrogen supply.Leucaena produced significantly more biomass, and its leaves had higher concentrations of nitrogen, phosphorous and potassium and lower C/N and C/P ratios than did those ofFlemingia. There was also evidence that the trees had a beneficial effect on other soil chemical properties; under the hedgerows, particularly those ofLeucaena, there were higher levels of organic carbon, Mg, K and ECEC, and pH values were also highest. It is suggested that higher levels of organic carbon in the alley crop treatments were responsible for the improvements observed in soil physical properties. Lower bulk density, lower penetration resistance, and a higher infiltration rate and pore volume fraction were measured in the alley crops, although there was no significant change in the soil water release parameters. A deteriorating effect of constant applications of nitrogen fertiliser on soil fertility was observed; as the level of urea application increased, there were significant decreases in Mg, K and pH, increases in Al and soil acidity, and higher penetrometer resistance. These results highlight the urgent need for further research on biological methods of maintaining soil fertility.
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  • 47
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    Antonie van Leeuwenhoek 60 (1991), S. 225-234 
    ISSN: 1572-9699
    Keywords: chemostat ; growth yield ; growth limitation ; multiple nutrient limitation ; carbon ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Simultaneous limitation of microbial growth by two or more nutrients is discussed for dual carbon/nitrogen-limited growth in continuous culture. The boundaries of the zone where double-limited growth occurs can be clearly defined from both cultivation data and cellular composition and they can be also predicted from growth yield data measured under single-substrate-limited conditions. It is demonstrated that for the two nutrients carbon and nitrogen the zone of double nutrient limitation is dependent on both the C:N ratio of the growth medium and the growth (dilution) rate. The concept on double-(carbon/nitrogen)-limited growth presented here can be extended to other binary and multiple combinations of nutrients.
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  • 48
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    Biodegradation 20 (1993), S. 195-212 
    ISSN: 1572-9729
    Keywords: denitrification ; lake ; mass balance ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen mass balances for seven unproductive lakes and 20 forested catchments in central Ontario were measured between 1977 and 1989. Average annual lake denitrification rates calculated with the N/P ratio method were strongly correlated with summer anoxic factor (extent of surficial sediment anoxia) whereas denitrification rates calculated with a210Pb sediment N accumulation method were poorly correlated with the anoxic factor suggesting that the N/P method is superior. Substantial denitrification occurred in all lakes — an average of 36% of TN inputs or 75% of the net gain. On a regional area-weighted basis, 67% of bulk atmospheric TN deposition was stored or denitrified terrestrially, 12% was denitrified in lakes, 4% was stored in lake sediments, and 17% was exported from lakes. N/P ratios were generally less in streams than in precipitation suggesting preferential N retention in catchments, whereas the N/P ratios in lake outputs were slightly higher than lake input ratios, suggesting preferential P retention in lakes. This is consistent with the notion that P-limited lakes can exist adjacent to N-limited forests.
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  • 49
    ISSN: 1572-9680
    Keywords: Argania spinosa ; micro-elements ; nitrogen ; phosphorus ; V.A. mycorrhization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Résumé L'influence de la mycorhization V.A. sur la nutrition minérale de 2 clones d'Arganier (Argania spinosa) a été étudiée sur des plantules micropropagées in vitro poussant en conditions contrôlées. L'inoculation (qui augmentait la production de matière sèche d'un facteur 4,5) accroit également la teneur des plantes en phosphore, notamment dans les feuilles, et les plantes mycorhizées mobilisent 15 fois plus de phosphore que les plantes non inoculées. La teneur en azote est légèrement plus faible chez les plantes mycorhizées mais au total ces dernières exportent 3 fois plus d'azote. L'absorption des micro-éléments est aussi affectée par l'inoculation, qui accroit les teneurs des plantes en Fe, Zn et Cu. La nutrition minérale des deux clones étudiés semble affectée par le rapport racines/parties aériennes et d'autres caractéristiques génétiques, comme l'efficacité de translocation du fer. Ces résultats nous permettent de comprendre en quoi son système racinaire profond et mycorhizé permet à l'Arganier non seulement de pousser dans des zones arides aux sols pauvres, mais aussi d'améliorer la fertilité des couches supérieures du sol par l'effet litière.
    Notes: Abstract The influence of V.A. mycorrhization on mineral nutrition of 2 clones ofArgania spinosa was studied with in-vitro micropropagated plantlets grown in confined medium under controlled conditions. Inoculation, which increased dry matter production by a factor of 4.5, also increased P concentration in the plant, especially in the leaves, and the mycorrhizal plants mobilized 15 times more P than control plants. N concentration was slightly lower in mycorrhizal plants, but total N content was 3 times higher. Uptake of micro elements was also affected, inoculation increasing plant Fe, Zn and Cu content. Mineral nutrition in the test clones seemed affected by root/shoot ratio and other genetically-related characteristics, such as Fe translocation efficiency. These results help us to understand how its deep mycorrhizal root system might allowArgania spinosa not only to grow in infertile arid areas but also to improve top-soil fertility by a litter effect.
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  • 50
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    Antonie van Leeuwenhoek 65 (1994), S. 179-182 
    ISSN: 1572-9699
    Keywords: Aspergillus ; fungus ; catabolism ; activation ; repression ; nitrogen ; carbon ; zinc fingers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheamdS gene codes for an acetamidase enzyme that hydrolyses acetamide to acetate and ammonium thus providingA. nidulans with a source of carbon and nitrogen. The exceptionally favourable genetics of this system combined with molecular analysis have enabled many regulatory circuits affectingamdS to be identified genetically. Characterization of the regulatory genes and the definition of the cis-acting sites involved have been done using bothin vivo andin vitro mutagenesis. Recent results on the analysis of the system are presented.
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  • 51
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    Agroforestry systems 21 (1993), S. 1-10 
    ISSN: 1572-9680
    Keywords: silvo-pasture ; compaction ; cattle traffic ; penetrometer ; bulk density ; nitrogen ; seedlings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper reports on the extent of soil compaction due to cattle traffic around hardwood and softwood tree seedlings established in existing pasture, and subject to cattle pressure. A higher soil penetrometer resistance in the grazed areas pointed to a significant change in soil structure (i.e. dry bulk density) as a result of cattle traffic in the area. In a related experiment comparing the effect of three different levels of soil compaction on tree seedling growth and nitrogen cycling it was found that water infiltration and nitrogen uptake were reduced in soils treated with a medium and high level of compactive effort. This resulted in a slower rate of growth of the tree seedlings. The addition of an additional nitrogen source improved seedling growth in both the medium and high density compactive treatments.
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  • 52
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    Biodegradation 10 (1990), S. 309-328 
    ISSN: 1572-9729
    Keywords: estuaries ; groundwater ; nitrogen ; nitrogen cycle ; nitrogen loading
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We examined the importance of nitrogen inputs from groundwater and runoff in a small coastal marine cove on Cape Cod, MA, USA. We evaluated groundwater inputs by three different methods: a water budget, assuming discharge equals recharge; direct measurements of discharge using bell jars; and a budget of water and salt at the mouth of the Cove over several tidal cycles. The lowest estimates were obtained by using a water budget and the highest estimates were obtained using a budget of water and salt at the Cove mouth. Overall there was more than a five fold difference in the freshwater inputs calculated by using these methods. Nitrogen in groundwater appears to be largely derived from on site septic systems. Average nitrate concentrations were highest in the region where building density was greatest. Nitrate in groundwater appeared to behave conservatively in sandy sediments where groundwater flow rates were high (〉 11/m2/h), indicating that denitrification was not substantially reducing external nitrogen loading to the Cove. Nitrogen inputs from groundwater were approximately 300 mmol-N/m3/y of Cove water. Road runoff contributed an additional 60 mmol/m3/y. Total nitrogen inputs from groundwater and road runoff to this cove were similar in magnitude to river dominated estuaries in urbanized areas in the United States.
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  • 53
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    Biodegradation 14 (1991), S. 167-191 
    ISSN: 1572-9729
    Keywords: leaf longevity ; nitrogen ; nutrient use efficiency ; phosphorus ; requirement ; retranslocation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Aboveground nitrogen (N) and phosphorus (P) requirement, retranslocation and use efficiency were determined for 28-year-old red oak (Quercus rubra L.), European larch (Larix decidua Miller), white pine (Pinus strobes L.), red pine (Pinus resinosa Ait.) and Norway spruce (Picea abies (L) Karst.) plantations on a similar soil in southwestern Wisconsin. Annual aboveground N and P requirements (kg/ha/yr) totaled 126 and 13 for red oak, 86 and 9 for European larch, 80 and 9 for white pine, 38 and 6 for red pine, and 81 and 13 for Norway spruce, respectively. Nitrogen and P retranslocation from current foliage ranged from 81 and 72%, respectively, for European larch, whereas red pine retranslocated the smallest amount of N (13%) and Norway spruce retranslocated the smallest amount of P (18%). In three evergreen species, uptake accounted for 72 to 74% of annual N requirement whereas for two deciduous species retranslocation accounted for 76 to 77% of the annual N requirement. Nitrogen and P use (ANPP/uptake) was more efficient in deciduous species than evergreen species. The results from this common garden experiment demonstrate that differences in N and P cycling among species may result from intrinsic characteristics (e.g. leaf longevity) rather than environmental conditions.
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  • 54
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    Biodegradation 14 (1991), S. 209-224 
    ISSN: 1572-9729
    Keywords: ground water ; hydrology ; nitrogen ; mass balance ; nutrient retention ; swamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ground water inputs and outputs of N were studied for a small ground water discharge swamp situated in a headwater drainage basin in southern Ontario, Canada. Darcy's equation with data for piezometers was used to measure inputs of shallow local ground water at the swamp margin and deep regional ground water beneath the swamp. Ground water flux was also quantified by measuring ground water discharge to the outlet stream draining the swamp in combination with a chemical mixing model to separate shallow and deep ground water components based on chloride differences. Estimates of shallow ground water flux determined by these two approaches agreed closely however, the piezometer data seriously underestimated the deep ground water input to the swamp. An average ground water input-output budget of total N (TN) total organic nitrogen (TON) ammonium (NH4 +-N) and nitrate (NO3 --N) was estimated for stream base flow periods which occurred on an average of 328 days each year during 1986–1990. Approximately 90% of the annual NO3 --N input was contributed by shallow ground water at the swamp margin. Deep ground water represented about 65% of the total ground water input and a similar proportion of TON and NH4 +-N inputs. Annual ground water NO3 --N inputs and outputs were similar whereas NH4 +-N retention was 4 kg ha-1 representing about 68% of annual ground water input. Annual TON inputs in ground water exceeded outputs by 7.7 kg ha (27%). The capacity of the swamp to regulate ground water N fluxes was influenced by the N chemistry of ground water inputs and the hydrologic pathways of transport within the swamp.
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  • 55
    ISSN: 1572-9729
    Keywords: calcium ; fine roots ; nitrogen ; northern hardwood ; nutrient dynamics ; seasonality ; soils ; sulfur ; vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seasonal dynamics of S, Ca and N were examined at the Huntington Forest, a northern hardwood ecosystem in the central Adirondacks of New York for a period of 34 months (1985–1988). Solute concentrations and fluxes in bulk precipitation, throughfall (TF) and leachates from the forest floor, E horizon and B horizon were quantified. Both above and below-ground elemental fluxes mediated by vegetation (e.g. uptake, litter inputs, and fine roots production) were also determined. The roles of abiotic and biotic processes were ascertained based on both changes in solute concentrations through the strata of the ecosystem as well as differences between dormant and growing seasons. Concentrations of SO4 2−, NO3 −, NH4 + and Ca2+ were greater in TF than precipitation. Forest floor leachates had greater concentrations of SO4 2−, NO3 − + NH4 + and Ca2+ (9, 6 and 77 µeq L−1, respectively) than TF. There were differences in concentrations of ions in leachates from the forest floor between the dormant and growing seasons presumably due to vegetation uptake and microbial immobilization. Concentrations and fluxes of NO3 − and NH; were greatest in early spring followed by a rapid decline which coincided with a demand for N by vegetation in late spring. Vegetation uptake (44.7 kg N ha−1 yr−1 ) could account for the low leaching rates of N03 −. Within the mineral soil, changes with soil depth and the absence of seasonal patterns suggest that cation exchange (Ca+) or anion sorption (SO4 2−) are primarily responsible for regulating solute concentrations. The increase in SO4 2− concentration after leachates passed through the mineral soil may be attributed to desorption of sulfate that was adsorbed during an earlier period when SO4 2− concentrations would have been greater due to elevated S inputs.
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  • 56
    ISSN: 1572-9699
    Keywords: survival ; starvation ; stress ; Vibrio ; carbon ; nitrogen ; phosphorus ; protein synthesis ; carbon starvation stimulon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Non-differentiating bacteria adapt to starvation induced growth arrest by a complex turn-on/turn-off pattern of protein synthesis. This response shows distinct similarities with those of spore formation in differentiating organisms. A substantial amount of information on the non-growth biology of non-differentiating bacteria can be derived from studies onVibrio strains. One important result is that carbon rather than nitrogen or phosphorus starvation leads to the development of a starvation and stress resistant cell in these organisms. Hence, we have attempted to characterize the carbon starvation stimulon. By the use of two-dimensional gel electrophoresis of pulse-labelled cells and transposon mutagenesis, using reporter gene constructs, the identity and function of some members of the carbon starvation stimulon have been elucidated. Moreover, regulatory genes of the starvation response have been identified with these techniques. Current studies primarily address the identity and function of these genes. The role of transcript modification and stability for both long term persistence during starvation as well as the efficient recovery of cells which occurs upon nutrient addition is also addressed. It is suggested that an understanding of the functionality of the translational machinery is essential for the understanding of these adaptive pathways. This contribution also discusses the diversity of the differentiation-like response to starvation in different bacteria and whether a general starvation induced programme exists.
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  • 57
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    Entomologia experimentalis et applicata 62 (1992), S. 29-36 
    ISSN: 1570-7458
    Keywords: Alkaloids ; cinnabar moth ; insect genetics ; larval performance ; Lepidoptera ; nutritional ecology ; nitrogen ; sugar ; Tyria jacobaeae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a laboratory experiment using full-sibs, 60% of the variation in pupal weight of the monophage Tyria jacobaeae L. (Lepidoptera, Arctiidae) could be explained by variation in the nitrogen concentration of the food plant, Senecio jacobaea L. and only 4% by variation in sugar concentration. Larval weight and growth rates of young and old larvae were also positively correlated with nitrogen and sugar concentration. Developmental time was negatively correlated with nitrogen concentration. In a second experiment full-sib families differed significantly in larval weight at day 7, mortality, growth rate and developmental time. Pupal weight did not differ significantly among families, but was positively correlated with nitrogen concentration of Senecio. Larval performance was not significantly influenced by concentrations of sugars or alkaloids. We conclude that larval performance of Tyria during most of the larval period is mainly determined by genetic factors, but pupal weights are primarily determined by nitrogen concentration of the food plant.
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  • 58
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    Ecological research 5 (1990), S. 111-130 
    ISSN: 1440-1703
    Keywords: Big woody materials ; Decomposition rate ; Foothill diperocarp forest ; nitrogen ; turnover time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dynamics of aboveground big woody organs over 10 cm diameter was studied at a mature foothill dipterocarp forest in West Sumatra. The biomass of big woody organs was estimated to be 519 m3 ha−1 or 408 metric ton ha−1 by means of a pipe model theory. The diameter distribution showed a convex curve and the mode was found at a diameter of about 20 cm. The standing mass of big dead woody litter on the forest floor was 116 m3 ha−1, which accounted for 22% by voume or 9.5% by weight of the biomass of living organs respectively. Thedbh observation with two 1-ha plots for 4 yr and 5 yr respectively revealed that the average net production rate was 9.5 ton ha−1 yr−1. The death rate (7.9 ton ha−1 yr−1) accounted for 83% of the net production rate and was nearly equivalent to the decay rate (7.5 ha−1 yr−1) of dead wood on the forest floor. The balance between the death and decay rates was confirmed for each diameter class. Average turnover periods for big woody organs and dead woody litter were estimated to be 43 and 8.1 yr, respectively. Standing masses of live anddead woody materials accumulated in the study forest were approximately equal to those obtained in a mature tropical lowland rainforest, whereas the flow rates were lower, being only 70% of the corresponding values.
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  • 59
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    International journal of thermophysics 14 (1993), S. 699-725 
    ISSN: 1572-9567
    Keywords: argon ; caloric properties ; density ; equation of state ; Helmholtz function ; methane ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In order to describe the thermodynamic behavior of methane, argon, and nitrogen in the so-called “natural-gas region,” namely, from 270 to 350 K at pressures up to 30 MPa as accurate as possible with equations of a very simple form, new equations of state for these three substances have been developed. These equations are in the form of a fundamental equation in the dimensionless Helmholtz energy; for calculating the pressure or the density, the corresponding equations explicit in pressure are also given. The residual parts of the Helmholtz function representing the behavior of the real gas contain 12 fitted coefficients for methane, 8 for argon, and 7 for nitrogen. The thermodynamic relations between the Helmholtz energy and the most important thermodynamic properties and the needed derivatives of the equations are explicitly given; to assist the user there is also a table with values for computer-program verification. The uncertainties when calculating the density ρ, the speed of sound w, the isobaric specific heat capacity c p, and the isochoric specific heat capacity c v are estimated as follows. For all three substances it is Δρ/ρ≤±0.02 % for p≤ 12 MPa and Δρ/ρ ≤ ±0.05% for higher pressures. For methane it is Δw/w≤±0.02% for p≤10 MPa and Δw/w≤+-0.1% for higher pressures; for argon it is Δw/w≲-0.1 % for p≤ 7 MPa, Δw/w≤±0.3 % for 7 〈p≤30 MPa; and for nitrogen it is Δw/w≤±0.1% for p≤1.5 MPa and Δw/w±0.5% for higher pressures. For all three substances it is Δc p/c p≤±1 % and ΔC v/C v≤±1 % in the entire range.
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    International journal of thermophysics 15 (1994), S. 1211-1219 
    ISSN: 1572-9567
    Keywords: binary system ; butane ; carbon dioxide ; nitrogen ; ternary system ; vapor-liquid equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The system studied was nitrogen + carbon dioxide +n-butane at 250 and 270 K and at pressures from 1.5 to 14 MPa. The Peng-Robinson equation was used to model the results, since it is the most widely accepted equation of state in the gas processing industry. In general, the predictions are most accurate at low and moderate pressures and poorest at high pressures, especially near the critical region.
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  • 61
    ISSN: 1573-5036
    Keywords: critical concentration ; deficiency ; diagnosis ; growth rate ; lettuce ; luxury consumption ; nitrogen ; nitrate ; nutrient requirement ; petiole sap ; phosphorus ; phosphate ; potassium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A method is described for determining the way in which growth rate varies with plant nutrient concentration using a simple nutrient interruption technique incorporating only 2 treatments. The method involves measuring the changes in growth and nutrient composition of otherwise well-nourished plants after the supply of one particular nutrient has been withheld. Critical concentrations are estimated from the relationship between the growth rate (expressed as a fraction of that for control plants of the same size which remained well-nourished throughout) and the concentration of the growth-limiting nutrient in the plants as deficiency developed. Trials of the method using young lettuce plants showed that shoot growth rate was directly proportional to total N (nitrate plus organic N) concentration, and linearly or near-linearly related to K and P concentration over a wide range; the corresponding relationship for nitrate was strongly curvi-linear. Critical concentrations (corresponding to a 10% reduction in growth rate) determined from these results were similar to critical values calculated from models derived from field data, but were generally higher than published estimates of critical concentration (based on reductions in shoot weight) for plants of a similar size. Reasons for these discrepancies are discussed. Nitrate, phosphate or potassium concentrations in sap from individual leaf petioles were highly sensitive to changes in shoot growth rate as deficiency developed, with the slope of the relationships varying with leaf position, due to differences both in their initial concentration and in the rates at which they were utilized in individual leaves. Each nutrient was always depleted more quickly in younger leaves than in older ones, providing earlier evidence of deficiency for diagnostic purposes. Although the plants were capable of accumulating nitrate, phosphate and potassium well in excess of that needed for optimum dry matter production during periods of adequate supply, the rate of mobilization of these reserves was insufficient to prevent reductions in growth rate as the plants became deficient. This brings into question the validity of the conventional concept that luxury consumption provides a store of nutrients which are freely available for use in times of shortage. The implications of these results for the use of plant analysis for assessing plant nutrient status are discussed.
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  • 62
    ISSN: 1573-5044
    Keywords: carbon ; elevated CO2 ; nitrogen ; suspension culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A photoautotrophic soybean suspension culture (SB-P) was used to study CO2 assimilation while exposed to elevated or ambient CO2 levels. These studies showed that under elevated CO2 (5% v/v) malate is the dominant fixation product, strongly suggesting that phosphoenolpyruvate carboxylase (PEPCase) is the primary enzyme involved in carbon fixation in these cells under their normal growth conditions. Citrate and [aspartate + glutamate] were also significant fixation products during fifteen minutes of exposure to 14CO2. During the ten minute unlabeled CO2 chase however, 14C-malate continued to increase while citrate and [aspartate + glutamate] declined. Fixation of 14CO2 under ambient CO2 levels (0.037%) showed a very different product pattern as 3-phosphoglycerate was very high in the first one to two minutes followed by increases in [serine + glycine] and [aspartate + glutamate]. Hexose phosphates were also quite high initially but then declined relatively rapidly. Thus, the carbon fixation pattern at ambient CO2 levels resembles somewhat that seen in C3 leaf cells while that seen at elevated CO2 levels more closely resembles that of a C4 plant. The initial fixation product of C3 plants, 3-PGA, was never detectable under high CO2 conditions. These data suggest that an in vitro photoautotrophic system would be suitable for studying carbon fixation physiology during photosynthetic and non-photosynthetic growth.
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  • 63
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    Plant growth regulation 10 (1991), S. 185-195 
    ISSN: 1573-5087
    Keywords: mustard ; Brassica juncea ; nitrogen ; chlormequat chrloride ; seed oil ; seed yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The growth of mustard was increased significantly when treated with up to 80 kg N ha−1 (N80). Spraying with (2-chloroethyl) trimethylammoniumchloride (chlormequat chloride) increased seed yield and seed protein content. Spraying nitrogen fertilized plots with chlormequat chloride, increased leaf area, leaf area ratio, leaf area duration, number of siliquae plant−1, number of seeds siliqua−1 and length of siliqua. Reducing, non-reducing and total sugars in the leaves at 80 days after sowing were also affected significantly. Chlorophyll ‘a’, ‘b’ and total chlorophyll were little affected. The number of siliquae plant−1 was highly correlated with seed yield in both the seasons of experimentation. The correlation coefficient value (γ) was 0.586 in 1982/83 and 0.912 in 1983/84. The total accumulation of nutrients, i.e. nitrogen, phosphorus and potassium in seed and straw was significantly affected by N80 × chlormequat chloride interaction.
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  • 64
    ISSN: 1573-5087
    Keywords: Lemna gibba ; cytokinins ; isopentenyladenosine ; zeatinriboside ; abscisic acid ; nitrogen ; phosphorus ; relative growth rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The relationship between endogenous cytokinin content and relative growth rate (RGR) was studied in cultures of Lemna gibba L. G3 supplied with daily doses of mineral nutrients that were increased exponentially over time. At the optimal level of nutrient supply the RGR was 30–35% day-1. The RGR was regulated by adjusting the rate of nitrogen supply, or it was restricted by addition of 0.5 μM abscisic acid (ABA). Another approach used to investigate the specific roles of nitrogen (N) and phosphorus (P), was to transfer optimally growing plants to media without N or P but otherwise complete. The plants were harvested at regular intervals for determination of the RGR and levels of cytokinins of the isopentenyladenosine (iPA) and zeatinriboside (ZR) types with an enzyme-linked immunosorbent assay (ELISA). Levels of both iPA- and ZR-type cytokinins decreased when nitrogen was applied to cultures in growth limiting amounts. The cytokinin levels decreased more rapidly than the RGR when either N or P was lacking in the medium, suggesting an early influence of nutrient availability on cytokinin levels which in turn may induce adaptive response by the plant. RGR retardation induced by ABA did not affect cytokinin levels during the first 4 days of the treatment, and the later effects were small. The experiments gave no indication that ABA is involved in the adaptation response of Lemna plants to nutritional stress.
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  • 65
    ISSN: 1573-5095
    Keywords: actinorhizae ; fertilization ; Frankia ; nitrogen ; nodulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To determine if inoculation increases nodulation and yield of bare-root red alder (Alnus rubra Bong.), fumigated nursery plots were treated with inoculum and ammonium sulfate (28 kg N ha−1) in a factorial experiment. Inoculum was alder soil with 100 infective units of Frankia g−1. Seedlings were evaluated for nodulation at age 10 wk and when lifted, at age 9 mo. Inoculation produced earlier and more extensive nodulation and increased seedling root collar diameter, height, and dry weight. Fertilization decreased seedling height, but did not decrease nodulation. No interaction of fertilization with inoculation was found. Inoculated unfertilized plots had the highest yield of packable seedlings (257 m−2), and uninoculated fertilized seedlings had the lowest yield (126 m−2).
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  • 66
    ISSN: 1573-5095
    Keywords: foliage ; grafting ; nitrogen ; phosphorus ; Pinus caribaea ; rootstock ; scion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Both scion and rootstock clones significantly influenced scion elongation and concentrations of nitrogen and phosphorus in the scion foliage. Scion clone was the more important determinant. Scion clone × rootstock clone interactions were not significant. The ability of a clone to elongate as a scion was not correlated with its capacity to promote or retard scion elongation when used as a rootstock. Genetic differences in foliar nutrient concentrations appeared to reflect levels of nutrient demand, rather than the ability of roots to absorb nutrients. Nutrient demand of the rootstock can also explain negative correlations between nitrogen levels in rootstock clones and levels of both nitrogen and phosphorus in the scions. There was no significant relationship between scion elongation and foliar nitrogen concentrations of either rootstock or scion. The weak relationship between scion elongation and concentration of phosphorus in the rootstock apparently resulted from tissue dilution.
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  • 67
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    Plant and soil 123 (1990), S. 155-159 
    ISSN: 1573-5036
    Keywords: cultivars ; nitrogen ; roots ; tropic climate ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Due to the high price of fertilizer the input of N for grain maize production must be kept low in many parts of the world. Low input cultivars have been suggested to meet this requirement. Screening of a group of tropical cultivars revealed two high input, two low input and two intermediate cultivars with regard to N utilization. One of the causes of an interaction between genotype and N fertilization might be differences in root morphology. Screening for such differences at an early seedling stage would facilitate the selection for low input varieties. This hypothesis was tested by growing seedlings of the six varieties at different levels of N until the fourth leaf stage. There was no significant interaction between genotypes and N supply. At low and medium N supply, the total seedling biomass was the same but at low N a higher proportion of dry weight was found in the roots. Total biomass was reduced at high N. Low input and intermediate cultivars had higher shoot and root dry weights than did high input cultivars but no significant differences in root surface area were found. Root surface area was greatest at low N. Number and total length of seminal roots were significantly lower for high input varieties which, in combination with a relatively high root surface area, points to an intensive root type.
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  • 68
    ISSN: 1573-5036
    Keywords: grassland ; leaching ; leaf litter ; macro-organic matter ; mineralization ; nitrogen ; ploughing ; roots ; stubble
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The amounts of organic matter in the stubble, litter, root and soil macro-organic matter fractions of two swards of perennial ryegrass that had received normal applications of either fertilizer or cattle urine were, on average for the four fractions, about 3000, 500, 11,500 and 8,800 kg ha−1. The swards had been established 8 or 15 years previously and each was sampled at intervals over a period of about one year. The amounts of N contained in the four fractions were, on average, 68, 12, 249 and 240 kg ha−1, a total of 569 kg N ha−1. With other swards, increasing rates of application of fertilizer N were found to have little effect on the amounts of organic matter in stubble and roots. Concentrations of N in the organic matter of the stubble and roots, however, increased significantly with increasing rate of fertilizer application, though, with stubble, moderate rates of application had little effect. Assessments based on these data, together with other published information, indicate that the amount of N mineralized from the combined stubble, litter, root and macro-organic matter fractions during the first year after ploughing may range from about 40 kg to at least 360 kg N ha−1 depending on the age of the sward and its recent management. The amount mineralized is likely to increase with age of sward, with increasing rate of fertilizer N and with utilisation by grazing rather than cutting.
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  • 69
    ISSN: 1573-5036
    Keywords: nitrogen ; pasture ; phosphorus ; plant ; P fertility status ; season ; soil ; temporal variations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Temporal variations in plant production, plant P and some soil P (and N) pools were followed over 21 months in two New Zealand pasture soils of widely different P fertility status. Plant growth rates, and herbage composition at the high-fertility site, were closely linked to soil water use, with growth rates falling when soil water deficits exceeded 60 mm. Herbage P concentrations reflected P fertility, and varied with season, being generally higher in winter and lower in summer. A similar temporal pattern was also observed for labile organic P (NaHCO3-extractable P0) in both soils. In the low-fertility soil in spring, net mineralization was especially strong, but from early winter net immobilization occurred. Surprisingly, Olsen P also changed temporally in the high-fertility soil. The microbial biomass remained fairly constant throughout the year, whereas the P content of the biomass varied seasonally. Although microbial biomass was not a useful index of soil fertility, highest microbial P0 contents coincided with periods of maximum labile P0 mineralization, when herbage production was also at a peak. Net N-mineralization in the low-fertility soil, in contrast to the high-fertility soil, was low but varied seasonally, under standardised incubation conditions. Soil P and N dynamics were apparently synchronised in the low-fertility soil through soil microbial processes, with mineral N being negatively correlated with microbial P0 in samples collected two months later. The results of this investigation suggest that the demands of rapid and sustained pasture growth in spring and early summer can best be met by maximising the build-up of organic matter during the preceding autumn and winter. This practice could help to alleviate the common problem of feed shortage in North Island hill country pastures in late winter-early spring.
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  • 70
    ISSN: 1573-5036
    Keywords: calcium ; copper ; desert ; ground water ; iron ; magnesium ; manganese ; nitrogen ; phosphorus ; Prosopis glandulosa ; rooting patterns ; sodium ; symbiotic nitrogen fixation ; trace metals ; water table ; water use efficiency ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Mesquite plants (Prosopis glandulosa var. Torreyana) were grown in 2-m long columns 20 cm in diameter, and provided with a constant, stable ground water source 10 cm above the sealed base of the column. Ground water contained 0, 1 or 5 mM nitrate, or a mixed salt solution (1.4, 2.8, or 5.6 dS m-1) with the ionic ratios of ground water found in a field stand of Prosopis at Harper's Well (2.8 dS m-1). Water uptake in the highly salinized columns began to decrease relative to low salt columns when soil salinity probes 30 cm above the column base read approximately 28 dS m-1, a potential threshold for mesquite salt tolerance. Prosopis growth increased with increasing nitrate, and decreased with increasing salinity. Water use efficiency was little affected by treatment, averaging approximately 2 g dry matter L-1 water used. Most fine roots were recovered from a zone about 25 cm above the ground water surface where water content and aeration appeared to be optimal for root growth. Root-shoot ratio was little affected by nitrate, but increased slightly with increasing salinity. Plant tissue P concentrations tended to increase with increasing salinity and decrease with increasing N, approaching potentially deficient foliage concentrations at 5 mM nitrate. The whole-plant leaf samples increased in sodium concentration both with added salt and with added nitrate. Foliar manganese concentrations increased with increasing salt in the absence of nitrate. Concentrations of sodium in leaves were low (〈10 g kg-1), considering the high salt concentrations in the ground water. Prosopis appears to exclude sodium very effectively, especially from its younger leaves. Although Prosopis is highly salt tolerant, the degree to which it utilizes soil nitrate in place of biologically fixed N may lower its salinity tolerance and affect its nutrient relations in phreatic environments.
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  • 71
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    Plant and soil 123 (1990), S. 67-71 
    ISSN: 1573-5036
    Keywords: Dalbergia sissoo ; fertilization ; nitrification ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of added ammonium, phosphorus, potassium, and gypsum on net nitrogen mineralization was studied in soil beneath a six-year-old plantation of the N2-fixing tree Dalbergia sissoo in Pakistan. Soil with and without amendments was placed in polyethylene bags and incubated, buried in the soil, for 30 days. After that time the soil was analyzed and net ammonium and nitrate production and net nitrogen mineralization were calculated. The addition of ammonium stimulated nitrification indicating that the process was substrate limited. The inhibition of nitrification by Nitrapyrin showed that the process is autotrophic in these soils. Gypsum addition lowered soil pH from 8.0 to 7.2 and significantly stimulated ammonification, nitrification and net nitrogen mineralization. The addition of potassium more than tripled the soil K:Na ratio. Net ammonium and nitrate production and net nitrogen mineralization all increased in this treatment. The addition of phosphorus had no significant effect on soil nitrogen dynamics.
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  • 72
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    Plant and soil 124 (1990), S. 33-37 
    ISSN: 1573-5036
    Keywords: leaf area ; nitrogen ; mineral nutrition ; phosphorus ; photoperiod ; Triticum ; wheat ; spikelet initiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of N and P on the number of spikelets of spring wheat (Triticum aestivum L.), grown in nutrient solution, were studied under 8 h and 16 h photoperiods. The effect of P was apparent only at a high rate of N supply and the effects of N were increased significantly at a high rate of P supply. Increasing N supply increased the number of spikelets due to a promotion of the rate of spikelet initiation. It also increased the leaf-blade area and the dry matter weight of the plants at the stage of terminal spikelet initiation. These effects of N were much greater under the short photoperiod than under the long photoperiod. The practical significance of these findings for winter-grown wheat in temperate regions is pointed out.
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  • 73
    ISSN: 1573-5036
    Keywords: eucalypt ; foliar analysis ; legume ; nitrogen ; phosphorus ; plant nutrients ; plant analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The sensitivity of tissue nutrient concentrations to changes in plant age and the supply of P and N was compared between leaves and associated twigs in two forest species. In a young regrowth stand, tissues were sampled on three occasions from the mid-crown position of karri (Eucalyptus diversicolor F. Muell.) and Bossiaea laidlawiana Tovey and Morris, a major understorey legume. Leaves and twigs were also sampled from young plants of B. laidlawiana growing in a mature eucalypt stand to which P treatments had been applied. Nitrogen application increased N concentrations in twigs of karri and B. laidlawiana, but not in leaves. Phosphorus application increased P concentrations in both leaves and twigs of karri but the average increases were proportionally greater in twigs (65%) than in leaves (36%). Over the sampling period, P concentrations in leaves declined, while those in twigs were relatively stable. In B. laidlawiana, P supply also had a larger effect on P concentrations in twigs than in leaves. Addition of 200 kg P ha−1 increased average P concentrations in twigs by 109% in the regrowth stand and by 215% in the mature stand while the corresponding increases in leaves were only 11% and 27%. Concentrations of other nutrients in both species were also affected by N and P application, the most notable being a decline in the concentrations of the minor nutrients, Zn and Cu, with increased P supply. The increased N concentrations in twigs of karri, and the increased P concentrations in tissues of both species, were associated with responses of karri to added N and P, and of B. laidlawiana to added P. This indicates that tissue concentrations of N and P were generally below critical concentrations where N and P were not applied. The results show that for these species twigs may be a better tissue than leaves for diagnosing deficiencies or predicting N and P requirements. The ratio of P concentrations in twigs to P concentrations in leaves also increased with added P. It is suggested that this ratio may be a useful index if it reduces the variability caused by sampling position within the crown or genetic differences between plants.
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  • 74
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    Plant and soil 129 (1990), S. 219-225 
    ISSN: 1573-5036
    Keywords: drying ; grassland ; heating ; microbial biomass ; mineralization ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A dwarf bamboo-type grassland soil (Thick High-humic Andosol) was nitrogen-limited for grass despite the presence of a considerable amount of microbial biomass N. By either treatments of air-drying and subsequent heating, the content of mineral N in the soil was increased by 3.7 g N and 11.7 g N m-2, respectively, after a 55-day incubation period. The efficiency of mineralized N for growth of orchardgrass was compared with nitrate-N added just before cultivation. The dry matter content of the grass increased from 81.7 g (control) to 169 g and to 337 g m-2 in the dried and in the heated soils, respectively, when N application was omitted. Of the mineral N released by air-drying and heating of the soil, 84% and 77% were absorbed by the grass, and 30% and 20% was assumed to be derived from microbial biomass, respectively. In contrast the grass apparently absorbed 54–56% of the 5 g nitrate-N m-2 added to the control and the air-dried soils. It was also noted that fungal biomass N had decreased by 1.5–1.9 g m-2 in the control soil after addition of 10 g nitrate-N m-2.
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  • 75
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    Plant and soil 127 (1990), S. 213-218 
    ISSN: 1573-5036
    Keywords: dry matter yield ; nickel ; nitrogen ; nutrient concentration ; wheat roots ; wheat tops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A glasshouse experiment was conducted to study the effect of Ni on the growth and nutrients concentration in wheat (Triticum aestivum Cv. WH 291) in the presence and absence of applied N as urea. Responses to N application were observed up to 120 μg N g−1 soil. No response to Ni was observed in the dry matter yield of wheat tops (leaves + stem) in the absence of applied N while in the presence of applied N, significant yield increases were obtained at 12.5μg Ni g−1 soil. Nickel was not toxic to wheat up to 50μg Ni g−1 soil in the presence of 120μg N g−1 soil. Nitrogen and Ni concentration in wheat tops and roots increased with increasing levels of applied N and Ni, respectively. Applied Ni had an antagonistic effect on N concentration. Similarly, N reduced the Ni concentration in the wheat tissues. Positive growth responses to Ni were associated with 22 and 15μg Ni g−1 in wheat tops, in the presence of applied N at 60 and 120μg N g−1 soil, while Ni toxicity was associated with 63, 92.5 and 112.5μg Ni g−1 in wheat tops, in the absence and presence of applied N at 60 and 120μg N g−1 soil, respectively.
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  • 76
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    Plant and soil 128 (1990), S. 21-30 
    ISSN: 1573-5036
    Keywords: allocation ; clearcut ; mineralization ; nitrogen ; prescribed fire
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Past and current work on biological processes related to nitrogen fluxes and cycling in natural and disturbed Mediterranean forest sites are discussed. In natural conditions, the main point reviewed is mineral nitrogen availability in the soil, and particularly the process of mineralization (ammonification, nitrification) in the field as well as nitrogen uptake by Pinus pinea. Some aspects of nitrogen translocation within the trees are also considered. Perturbation of the nitrogen status, and especially nitrogen mineralization, as a result of manipulation of forest sites are discussed by comparing both a holm oak coppice with a clearcut and a Pinus halepensis woodland before and after prescribed fire.
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  • 77
    ISSN: 1573-5036
    Keywords: ammonia volatilization ; denitrification ; grazing ; model ; nitrate leaching ; nitrogen ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The model simulates the cycling of N in grassland systems grazed by beef cattle and predicts the annual amount of N in liveweight gain, and the amounts lost through ammonia volatilization, denitrification and leaching, on the basis of fertilizer application and soil and site characteristics. It aims to provide a better understanding of the way in which these various factors interact in their influence on N transformations. The model has been programmed to run on IBM-compatible personal computers and responds rapidly to changes in input parameters. The model has been constructed from the average annual amounts of N passing through various components of the N cycle in ten field systems grazed by beef cattle. The amounts were either measured directly or were calculated from empirical sub-models, assuming a balance between inputs to, and outputs from the soil inorganic N pool. The model is given wide applicability through the inclusion of a mineralization sub-model which is sensitive to soil texture, sward age, previous cropping history, and climatic zone. Another important sub-model determines the partitioning of soil inorganic N to either plant uptake or the processes of loss: the proportion partitioned to plant uptake decreases as the total amount of soil inorganic N increases. Outputs from the model indicate that fertilizer N has a strong influence on ammonia volatilization, denitrification and leaching at a given site but that, over a range of sites with a given rate of fertilizer N, total loss and the proportions lost by the three processes are greatly influenced by the amount of N mineralized by the soil. The model indicates how fertilizer N should be matched with mineralization to limit gaseous and leaching losses and to achieve optimum efficiency of N use in grazing systems.
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  • 78
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    Plant and soil 133 (1991), S. 17-30 
    ISSN: 1573-5036
    Keywords: fertilisers ; foliage analysis ; growth studies ; Lotus ; Lupinus ; nitrogen ; nutrients ; phosphorus ; Trifolium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The phosphorus (P) responses of seven temperate perennial pasture legumes and two species of lupins were compared in a field trial over a range of nine P rates, from 0 to 800 kg ha-1. The two lupins produced more than 5 t ha-1 of dry matter in the absence of added P and showed no response to the fertiliser. In contrast, the pasture legumes initially failed to grow without added P and responded to applications of between 200 and 800 kg ha-1. At the higher rates of P, dry matter production of the pasture legumes was equivalent to that of the lupins. In the first 2 years of the trial; the most productive pasture legume species at the higher rates of added P were also the most productive at the lower rates. Phosphorus requirements for 90% of maximum yield varied greatly between species, but were closely related to maximum yield. Thus species with low P requirements for maximum yield were not necessarily P-efficient species. In the third and subsequent years of the trial Lotus corniculatus performed better than the other pasture legumes at the lower rates of added P. In contrast to other studies Lotus pedunculatus showed no ability to outyield Trifolium repens at low rates of P. Critical P concentrations of the pasture species for the late spring-early summer period declined in the order Trifolium repens (0.34%) 〉 Lotus pedunculatus (0.30%) 〉 Triofolium pratense (0.28%) 〉 Trifolium hybridum (0.27%) 〉 Trifolium ambiguum (0.26%) 〉 Lotus corniculatus (0.23%). Mineralisable nitrogen (N) levels were determined in soils under three species in the 7th year of the trial. At the lowest rates of added P, mineralisable N levels were much higher under Lupinus polyphyllus than under Trifolium repens or Lotus corniculatus. With increasing P rate, levels under the latter species increased, and at 100 kg P ha-1 were equivalent to those under the lupin with no added P.
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  • 79
    ISSN: 1573-5036
    Keywords: ammonium ; nitrogen ; Pseudotsuga menziesii ; rhizosphere pH ; sand culture ; shoot/root ratio ; specific root length (SRL) ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ammonium sulphate is a major component of the air pollutants deposited on forests in the Netherlands. Different amounts of NH4 + were added to Douglas-fir seedlings grown in tall containers of sand, to study the influence of high concentrations of NH4 + in the soil on the development of fine roots and the effects of nitrogen uptake on rhizosphere pH. At the end of this eight-month experiment part of the ammonium appeared to have nitrified into nitrate. High doses of ammonium negatively affected root length and root length per unit of dry matter (specific root length). Although Douglas fir shows a preferential ammonium uptake in nutrient solutions the increases in the pH of the rhizosphere in this experiment indicate that nitrogen was mostly taken up as nitrate. When the ammonium concentration in the soil is low, it cannot be taken up readily because of its low mobility in soil. Shoot growth was stimulated by high availability of nitrogen. The possible effects of high doses of ammonium on long-term forest vitality are discussed.
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  • 80
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    Plant and soil 125 (1990), S. 19-27 
    ISSN: 1573-5036
    Keywords: amino acid ; deficiency ; essentiality ; malate ; micronutrient ; nickel ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Barley (Hordeum vulgare L. cv. ‘Onda’) plants were grown in nutrient solutions supplied either 0 (no Ni added), 0.6, or 1.0 μM NiSO4. Plants supplied 0 μM Ni developed Ni deficiency symptoms; Ni deficiency resulted in the disruption of nitrogen metabolism, and affected the concentration of malate and various inorganic anions in roots, shoots, and grain of barley. The concentrations of 10 of the 11 soluble amino acids determined were 50–200% higher in 30-day-old shoots of plants supplied inadequate Ni levels than in shoots of Ni-supplied plants. The total concentration of all amino acids determined was higher in roots and grain of Ni-deficient plants. Concentrations of NO3 - and Cl- were also higher in Ni-deficient barley shoots than in Ni-sufficient barley shoots. In contrast, the concentration of alanine in shoots of Ni-deficient barley was reduced to one-third of the concentration in Ni-sufficient plants. The shoot concentrations of malate and SO4 2- were also depressed under Ni-deficient conditions. Total nitrogen concentration in grain, but not in shoots, of Ni-deficient plants was significantly increased over that found in Ni-adequate plants. Nickel deficiency results in marked disruptions of N metabolism, malate and amino acid concentrations in barley. These results are discussed in view of the possible roles of Ni in plants.
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  • 81
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    Plant and soil 135 (1991), S. 197-203 
    ISSN: 1573-5036
    Keywords: fertilization ; nitrogen ; kohlrabi ; root growth ; rooting depth ; spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract N fertilizer recommendatons are based on the Nmin content in the useable soil layer. However, for spinach, information from the literature differs for both depth of useable soil layer and N fertilizer recommendations. The objectives of these experiments were to study the importance of different soil zones for N supply to spinach and to kohlrabi, and to examine the relationship between N supply in the useable soil layer and yield of spinach. Field experiments with both crops showed that about 80% of total root length was in the upper 0–15 cm soil layer and less than 5% below 30 cm. Spinach roots were present in the 15–30 cm layer only during the last 2 weeks before harvest, whereas kohlrabi roots penetrated this layer already 4 weeks before harvest. Placement of NO3 below 30 cm depth did not influence root distribution. The top layer contributed about 80% to total N uptake for both crops. The 15–30 cm soil layer can maximally contribute 40–50 kg N ha-1. It is concluded that N fertilizer recommendations for both crops should be based on the Nmin content of the 0–30 cm soil layer. Maximum yield of spinach (300 dt f.m. ha-1) was obtained at 150 kg N supply ha-1. The nitrate residue was 50 kg N ha-1 at 0–30 cm in this treatment. It is argued that the nitrate residues at harvest could be decreased by delaying the harvest for a few days, at slightly suboptimal N supply.
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  • 82
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    Plant and soil 128 (1990), S. 97-101 
    ISSN: 1573-5036
    Keywords: calcium ; magnesium ; nitrogen ; nitrogen saturation ; Norway spruce ; nutritional imbalance ; Picea abies ; soil solution ; sulphur/nitrogen ratio ; tree nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Differences in nitrogen cycling and in the nutrition of trees are significantly coupled to the levels of nitrogen input and to the nitrate levels in the soil solution. Relatively high nitrogen supply can cause unbalanced nutrition on sites which contain either low or moderate amounts of other nutrients. This is indicated by low cation/nitrogen ratios in foliage and also by the S/N ratio falling temporarily below 0.030.
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  • 83
    ISSN: 1573-5036
    Keywords: anaerobic soils ; bacterial flush ; mineralisation ; nitrification ; nitrogen ; restoration ; soil perfusion ; soluble carbon ; stockpiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Topsoil stockpiled for 4 years resulted in an accumulation of NH4-N at depths of 1m or more in mound, as measured by an ammonia gas-sensing electrode. When leached with water these soils were also found to contain high concentrations of dissolved organic C below 1m. Both NH4-N and DOC were products of microbial mineralisation of soil organic matter that accumulated under anaerobic conditions. When these soils were restored a flush of decomposition took place, fuelled by labile organic matter and soluble nitrogen. Stockpiled soil which underwent an ammonium-rich perfusion regime in the laboratory indicated that in-mound soils rapidly attained greater nitrification potential than surface mound soils and also had greater potential for further mineralisation of organic matter to NH4-N. This further production was seen as a contribution from the bacterial flush, stimulated by the large labile-C pool already present. As the bulk of stored soil was anaerobic, restored soils were seen as potentially wasteful of their N-reserves; the fate of nitrogen and soluble carbon compounds in restored soils is discussed.
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  • 84
    ISSN: 1573-5036
    Keywords: disturbance ; fertilizer ; nitrogen ; nutrient enrichment ; phosphorus ; secondary succession ; species richness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of annual additions of mineral N and P (100 kg ha−1) on plant species composition and annual aboveground net primary production (ANPP) were investigated during the first three years following disturbance in a semi-arid ecosystem. Additions of N reduced richness of perennial plant species during years 2 and 3, while P reduced the number of perennial species only in year 3. From year 1 to year 2, annual and biennial species richness declined in all treatments while ANPP of annual species increased greatly. Added N increased ANPP of annual species while it decreased ANPP of most perennial species relative to the unfertilized control treatment. Community similarities were higher for the control and native vegetation than for other pairs of treatments using both species presence and plant production data. Nitrogen additions have retarded but not completely arrested secondary succession in this system.
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  • 85
    ISSN: 1573-5036
    Keywords: Fusarium oxysporum ; nitrogen ; peas ; phosphorus ; potassium ; Pythium vexans ; Rhizoctonia solani ; root-rots
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In field peas the application of nitrogen plus phosphorus, phosphorus plus potassium or nitrogen plus phosphorus plus potassium were effective in reducing severity of root rot caused by Rhizoctonia solani and with the combination of nitrogen plus phosphorus plus potassium in the case of Fusarium oxysporum. The fertilizers tested did not reduce disease caused by Pythium vexans or a combination of all pathogens.
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  • 86
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    Plant and soil 128 (1990), S. 115-126 
    ISSN: 1573-5036
    Keywords: ammonium ; mineralization ; nitrate ; nitrification ; nitrogen ; roots ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tomato root growth and distribution were related to inorganic nitrogen (N) availability and turnover to determine 1) if roots were located in soil zones where N supply was highest, and 2) whether roots effectively depleted soil N so that losses of inorganic N were minimized. Tomatoes were direct-seeded in an unfertilized field in Central California. A trench profile/monolith sampling method was used. Concentrations of nitrate (NO3 -) exceeded those of ammonium (NH4 +) several fold, and differences were greater at the soil surface (0–15 cm) than at lower depths (45–60 cm or 90–120 cm). Ammonium and NO3 - levels peaked in April before planting, as did mineralizable N and nitrification potential. Soon afterwards, NO3 - concentrations decreased, especially in the lower part of the profile, most likely as a result of leaching after application of irrigation water. Nitrogen pool sizes and rates of microbial processes declined gradually through the summer. Tomato plants utilized only a small percentage of the inorganic N available in the large volume of soil explored by their deep root systems; maximum daily uptake was approximately 3% of the soil pool. Root distribution, except for the zone around the taproot, was uniformly sparse (ca. 0.15 mg dry wt g-1 soil or 0.5 cm g-1 soil) throughout the soil profile regardless of depth, distance from the plant stem, or distance from the irrigation furrow. It bore no relation to N availability. Poor root development, especially in the N-rich top layer of soil, could explain low fertilizer N use by tomatoes.
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  • 87
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    Plant and soil 132 (1991), S. 293-296 
    ISSN: 1573-5036
    Keywords: boron ; nitrogen ; nitrate reductase activity ; phosphorus sorghum ; water soluble sugar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A foliar spray of boron (1 g borax litre-1) at the reproductive stage of sorghum varieties (PC 23, PC 9, PC 6 and HC 136), generally, increased the phosphorus content (24.5 per cent) and water soluble sugars (13.3 per cent) of seed coatings. The nitrogen content of a sorghum crop grown in a boron deficient soil improved only slightly (4.5 per cent) in spite of an elevated nitrate reductase activity (19.5 per cent). Such effects of boron seem to be associated with an increase in seed yield (14 per cent) and an improvement in the germination energy index. The magnitude of response was greater in variety HC 136 than the others.
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  • 88
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    Plant and soil 125 (1990), S. 109-117 
    ISSN: 1573-5036
    Keywords: ammonia ; environment ; grassland ; mechanical separation ; nitrogen ; slurry ; volatilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three experiments were conducted using a system of small wind tunnels to measure ammonia (NH3) volatilization from cattle slurry after surface application to land. In each experiment slurry was applied at a rate equivalent to 80 m3 ha-1, providing the equivalent of approximately 100 kg NH4 +-N ha-1. The first experiment compared NH3 volatilization from the liquid fraction obtained by mechanical separation of slurry with that from unseparated slurry. The total NH3 loss over six days from unseparated and separated slurry were very similar, being 38 and 35% respectively of the NH4 +-N applied. For the first five hours, the rate of NH3 loss was higher from the unseparated slurry, thereafter it was consistently lower. In the second experiment, slurry was ponded in a tray to examine whether impeded infiltration or changes in the NH4 + concentration or overall pH of the slurry influenced the rapid decline in rate soon after application that is characteristic of NH3 volatilization from animal slurries applied to land. It appeared, however, that other factors such as resistance to diffusion within the slurry and/or at the slurry surface were mostly responsible for the rapid decline in rate. In the third experiment, in which NH3 volatilization was measured from slurry applied to grassland or bare soil, the total loss from slurry applied to grassland was approximately 1.5 times that from slurry applied to bare soil.
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  • 89
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    Plant and soil 125 (1990), S. 119-128 
    ISSN: 1573-5036
    Keywords: ammonia ; application method ; application rate ; environment ; grassland ; nitrogen ; slurry ; volatilization ; wind speed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Three experiments were conducted to examine the influence of slurry application rate, wind speed and applying slurry in narrow bands on ammonia (NH3) volatilization from cattle slurry surface-applied to grassland. The experiments were conducted in the field using a system of small wind tunnels to measure NH3 loss. There was an inverse relationship between slurry application rate and the proportion of NH4 +-N volatilized. From slurry applied at 20, 40, 60, 80, 100 and 120 m3 ha-1, the respective proportions of NH4 +-N lost by NH3 volatization in 6 days were 60, 56, 49, 40, 44 and 44%. The negative relationship was most pronounced in the first 24 hours after application when 57–77% of the total loss for 6 days occurred. Wind speed had a positive effect on NH3 volatilization, although the effect was small in relation to the total loss; increasing the wind speed from 0.5 to 3.0 m s-1 increased the total 5 day loss by a factor of 0.29. The effect of wind speed was also most pronounced in the first 24 hours when much of the NH3 loss took place. The effect of reducing the surface area of the applied slurry was examined by comparing NH3 volatilization from slurry broadcast across plots with that applied in narrow bands. Although the rate of NH3 volatilization was considerably smaller from the banded application immediately after the slurry was applied, the difference between the treatments progressively narrowed until 2 days after application, after which a higher rate was maintained from the banded slurry. After 5 days the total loss from the banded application was 83% of that from broadcast slurry.
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  • 90
    ISSN: 1573-5036
    Keywords: mineralization capacity ; nitrogen ; principal components analysis ; soil incubation ; temperate humid zone ; soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The N mineralization capacity of 41 temperate humid-zone soils of NW Spain was measured by aerobic incubation for 15 days at 28°C and 75% of field capacity. The main soil factors affecting organic N dynamics were identified by principal components analysis. Ammonification predominated over nitrification in almost all soils. The mean net N mineralization rate was 1.63% of the organic N content, and varied according to soil parent materials as follows: soils on basic and ultrabasic rocks 〈 soils over acid metamorphic rocks 〈 soils developed over sediments 〈 soils over acid igneous rocks 〈 soils on limestone. The N mineralization capacity was lower in natural soils than in cropped soils or pastures. The accumulation of organic matter (C and N) seems to be due to poor mineralization which was caused, in decreasing order of importance, by high exchangeable H-ion levels, high Al and Fe gel contents and, to a lesser extent (though more markedly in cropped soils), by silty clay texture and exchangeable Al ions.
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  • 91
    ISSN: 1573-5044
    Keywords: Fragaria x ananassa ; in vitro ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The uptake of 15NO3 - and 15NH4 + has been examined in 5-,10- and 28-day-old micropropagated strawberry (Fragaria x ananassa Duch. cv. Kent) shoots rooted in one-half strength Murashige and Skoog (MS) liquid medium on cellulose plugs (Sorbarods). The results indicated that the plantlets absorbed both NO3 - and NH4 + during the culture with a greater uptake of NH4 + at 5 days of culture. Furthermore, a pronounced reduction in NO3 - and NH4 + uptake at 10 and 28 days of culture was observed within 6 h of the short-term uptake study. This reduction could be explained by the low CO2 concentration in test tubes during the photoperiod, since no reduction in nitrogen uptake occurred in the CO2 enriched condition. The results are interpreted as an indication of the important role for photosynthetic CO2 fixation in the process of nitrogen uptake by the plantlets during the rooting stage.
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  • 92
    ISSN: 1573-5044
    Keywords: carbohydrate ; germination ; Impatiens L. ; Impatiens platypetala L. ; nitrogen ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro germination of 20-day old immature ovules of Impatiens platypetala Lindl. was inhibited at concentrations as low as 50 mM sucrose or mannitol and 100 mM glucose. Younger ovules (12, 14, and 16 days old) were similarly inhibited at 100 mM sucrose. Inorganic nitrogen concentration did not affect germination regardless of ovule age, but seedling fresh weight was significantly less and abnormal development of seedlings was significantly increased by total inorganic nitrogen concentrations higher or lower than 30 mM (at a ratio of 20: 10 mM NO3 -: NH4 +) in the culture medium.
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  • 93
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    Plant cell, tissue and organ culture 21 (1990), S. 185-189 
    ISSN: 1573-5044
    Keywords: ammonium nitrate ; Malus ; nitrogen ; potassium nitrate ; tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of some macronutrients, especially NH4NO3 and KNO3, on root development of microcuttings from 3 apple scion cultivars is discussed. A reduction of the level of NH4NO3 in the medium from full strength to 1/4 strength significantly increased the percentage rooting of ‘Gala’ and ‘Royal Gala’, but not ‘Jonagold’. Further reduction of NH4NO3 level from 1/4 strength to zero significantly reduced the percentage of rooting in ‘Gala’ but not ‘Royal Gala’. ‘Jonagold’ rooted best at zero concentration NH4NO3. Without NH4NO3, rooting percentages were as high as 100% for all 3 cultivars when KNO3 was provided at full strength. The results show that adventitious roots can be induced on apple scion cultivars by media manipulation.
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  • 94
    ISSN: 1573-5044
    Keywords: Fatty acids ; hyoscyamine ; Hyoscyamus muticus ; nitrogen ; sucrose ; transformed root cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abatract The effect of carbon and nitrogen sources on two well-established hairy root clones, LBA1S and C58A, of Hyoscyamus muticus strain Cairo, were investigated. Both clones exhibited completely different patterns with regards to their growth rate, hyoscyamine accumulation, and fatty acid contents. Clone C58A grew faster and yielded more biomass (17.4 g l-1, in 21 days), but produced less hyoscyamine. The maximum hyoscyamine content (120 mg l-1) in clone LBA1S was reached in 28 days. Neither of the clones could use lactose or fructose as the sole carbon source, nor ammonium as the sole nitrogen source. The growth in the medium containing glucose was significantly reduced compared to that containing sucrose. Clone LBA1S was sensitive to the changes in sucrose concentration and an increase in ammonium in the culture medium, whereas C58A tolerated these changes better but was more sensitive to the increase in total nitrogen. Lipid synthesis was active in the exponential growth phase, and the total fatty acid content varied from 5 to 34 mg g-1 of dry root material. The major fatty acids were linoleic, palmitic and linolenic. There were considerable differences in the total amount of lipids and in their relative ratios when different nutrients were applied.
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  • 95
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    Plant and soil 142 (1992), S. 157-166 
    ISSN: 1573-5036
    Keywords: Acacia ; Eucalyptus regnans ; decomposition ; litterfall ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The N and P contents of the litter layer and the return of these nutrients in litterfall were measured in seven stands of Mountain Ash (Eucalyptus regnans) ranging in age from 5 years to about 250 years. Both annual litterfall and nutrient return were correlated with stand basal area and were high compared with other productive eucalypt forests. In contrast, the fall of dead eucalypt leaves was constant with stand age, demonstrating that sites are fully occupied at an early age. Similarly, amounts of N and P in total leaf fall (overstorey plus understorey) were constant with stand age, except for low amounts in the stand aged 40 years where Acacia spp., important fixers of atmospheric N, were not prevalent. The decomposition constant (k) of organic matter in the litter layer decreased with stand age, from 0.31 year-1 at age 5 years to 0.23 year-1 at age 250 years. These constants also applied to N and P, indicating a tight coupling between organic matter decomposition and release of these nutrients from litter. The litter layer released about 30 kg ha-1 of N at age 5 years, and about 70 kg ha-1 at age 80 years. These results are discussed in relation to growth of Mountain Ash following fire, and the subsequent retention and accumulation of N during stand development.
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  • 96
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    Plant and soil 142 (1992), S. 167-176 
    ISSN: 1573-5036
    Keywords: Eucalyptus regnans ; mineralization ; nitrification ; nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Laboratory and in situ rates of N mineralization in soils from Mountain Ash (Eucalyptus regnans) forests were measured fortnightly for two years in stands aged 9, 40, 80 and about 250 years (overmature), and for one year in stands aged 5 and 46 years. Rates of anaerobic mineralization (the laboratory test) showed little seasonal or annual variation. In contrast, rates of in situ mineralization varied markedly with season, being highest in spring and summer. Anaerobic mineralization was highly correlated with stand age to 80 years, but decreased between ages 80 and 250 years. In situ mineralization also decreased between these two ages, but otherwise was not related to stand age. Hence, the correlation between anaerobic and in situ mineralization along the age sequence was weak, suggesting that the anaerobic test is of maximum utility when this pool is in balance with inputs from decomposing litter (‘steady-state’ ecosystems). Nitrification was strong in stands aged 9, 46, 80 and 250 years and weak in stands aged 5 and 40 years. Within stands, the rate of nitrification during each period of in situ containment was highly dependent on the supply of NH4 ions. Between stands, annual rates of nitrification appear to be related to the balance between the N capital of the site, its rate of turnover, and the demand for N by heterotrophs and vegetation so that if NH4 supply is depleted, little is left for autotrophic nitrifiers.
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  • 97
    ISSN: 1573-5036
    Keywords: nitrogen ; phosphorus ; revegetation ; silica ; succession ; shrubland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fire is the principal means of stand renewal in big sagebrush-steppe communities of western North America. Plant growth following fire may be influenced by heat-induced changes in the nutrient status of the soil. Moreover, post-wildfire pioneer plant species may alter soil properties, and thereby, impact subsequent plant recruitment. Our study compared the growth and elemental content of big sagebrush (Artemisia tridentata), squirreltail (Elymus elymoides), cheatgrass (Bromus tectorum), and Indian ricegrass (Achnatherum hymenoides), grown under greenhouse conditions in post-wildfire and similar unburned soil. We also examined soil attributes following plant growth. Cheatgrass and squirreltail, grown in post-wildfire soil, had significantly (p≤0.05) greater aboveground mass than plants grown in unburned soil. As compared with unburned soil, post-wildfire soil engendered the following significant (p≤0.05) differences in leaf elemental content: 1) big sagebrush had higher levels of P and lower levels of Mn; 2) squirreltail accumulated more P and N; and 3) all grass species had higher SiO2 content. Following harvest of plants, post-wildfire soil generally contained significantly (p≤0.05) more KCl-extractable ortho-P, NH inf4 + , and SO 4 − , than unburned soil. Plant growth in both burned and unburned soils fostered a significant (p≤0.05) increase in the bicarbonate-extractable pool of P as compared with unplanted controls. Soil Kjeldahl-N was significantly (p≤0.05) greater after plant growth in burned treatments as compared with the control. This study demonstrates that post-wildfire soil can have a stimulatory effect on plant growth for some species. Squirreltail deserves consideration as a post-wildfire revegetation species. Furthermore, pioneer plant growth following wildfires can attenuate soil properties and therefore influence plant succession.
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  • 98
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    Plant and soil 164 (1994), S. 187-193 
    ISSN: 1573-5036
    Keywords: apatite ; biotite ; forest soil ; mineralization ; nitrogen ; nutrient additions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of slow (apatite, biotite) and fast-release nutrients (P, K, Mg) on C and N mineralization in acid forest soil were studied. These nutrients were applied alone or together with urea or urea and limestone. The production of CO2 in the soil samples taken one and three growing seasons after the application was lower in the soils treated with the fast-release nutrients than in the untreated soils. Similar reduction of microbial activity was not seen after the apatite and apatite+biotite treatments. In the first growing season, urea and urea+limestone enhanced CO2 production, but after three growing seasons, the opposite was true. Apatite and apatite+biotite added together with urea did not compensate for the decreasing effect of urea on the CO2 production. The addition of fast-release salts increased somewhat the concentration of NH inf4 sup+ in the soil and more NH4 + accumulated during laboratory incubation in the soil samples taken one growing season after the application. The urea addition immediately increased the concentrations of NH4 + and of NO3 − in the soil, but, three growing seasons after application, urea had only a slight increasing effect on mineral N content of the soil. Slow-release nutrients seem to have a more favourable effect than fast-release salts on nutrient turnover in acid forest soil.
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  • 99
    ISSN: 1573-5036
    Keywords: atmospheric deposition ; δ15N ; δ34S ; forest decline ; nitrogen ; Picea abies ; stable isotopes ; sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Concentrations and natural isotope abundance of total sulfur and nitrogen as well as sulfate and nitrate concentrations were measured in needles of different age classes and in soil samples of different horizons from a healthy and a declining Norway spruce (Picea abies (L.) Karst.) forest in the Fichtelgebirge (NE Bavaria, Germany), in order to study the fate of atmospheric depositions of sulfur and nitrogen compounds. The mean δ15N of the needles ranged between −3.7 and −2.1 ‰ and for δ34S a range between −0.4 and +0.9 ‰ was observed. δ34S and sulfur concentrations in the needles of both stands increased continuously with needle age and thus, were closely correlated. The δ15N values of the needles showed an initial decrease followed by an increase with needle age. The healthy stand showed more negative δ15N values in old needles than the declining stand. Nitrogen concentrations decreased with needle age. For soil samples at both sites the mean δ15N and δ34S values increased from −3 ‰ (δ15N) or +0.9 ‰ (δ34S) in the uppermost organic layer to about +4 ‰ (δ15N) or +4.5 ‰ (δ34S) in the mineral soil. This depth-dependent increase in abundance of 15N and 34S was accompanied by a decrease in total nitrogen and sulfur concentrations in the soil. δ15N values and nitrogen concentrations were closely correlated (slope −0.0061 ‰ δ15N per μmol eq N gdw −1), and δ34S values were linearly correlated with sulfur concentrations (slope −0.0576 ‰ δ34S per μmol eq S gdw −1). It follows that in the same soil samples sulfur concentrations were linearly correlated with the nitrogen concentrations (slope 0.0527), and δ34S values were linearly correlated with δ15N values (slope 0.459). A correlation of the sulfur and nitrogen isotope abundances on a Δ basis (which considers the different relative frequencies of 15N and 34S), however, revealed an isotope fractionation that was higher by a factor of 5 for sulfur than for nitrogen (slope 5.292). These correlations indicate a long term synchronous mineralization of organic nitrogen and sulfur compounds in the soil accompanied by element-specific isotope fractionations. Based on different sulfur isotope abundance of the soil (δ34S=0.9 ‰ for total sulfur of the organic layer was assumed to be equivalent to about −1.0 ‰ for soil sulfate) and of the atmospheric SO2 deposition (δ34S=2.0 ‰ at the healthy site and 2.3 ‰ at the declining site) the contribution of atmospheric SO2 to total sulfur of the needles was estimated. This contribution increased from about 20 % in current-year needles to more than 50 % in 3-year-old needles. The proportion of sulfur from atmospheric deposition was equivalent to the age dependent sulfate accumulation in the needles. In contrast to the accumulation of atmospheric sulfur compounds nitrogen compounds from atmospheric deposition were metabolized and were used for growth. The implications of both responses to atmospheric deposition are discussed.
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  • 100
    ISSN: 1573-5036
    Keywords: Alnus glutinosa ; carbon ; cold temperate climate ; lignin ; mesh bags ; nitrogen ; Orthic ; Sombric Brunisol ; plantation ; Populus ; root decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The decomposition of the roots (0–2 mm, 2–5 mm and 5–10 mm) of black alder (Alnus glutinosa (L.) Gaertn.) and hybrid poplar (Populus nigra L. X Populus trichocarpa Torr & Gray) was followed over a 462-day period in pure and mixed plantings in southern Quebec. Small roots of alder had the highest initial concentrations of nitrogen and lignin, and lost 9 and 10% less mass than medium and large roots, respectively. Large roots of poplar had the highest lignin-to-nitrogen ratio and showed the smallest loss of mass over the total incubation period. Slow root decomposition of black alder and hybrid poplar was characterized by a greater proportion of initial root nitrogen immobilized per unit of carbon respired. Lignin concentration in roots of alder and poplar increased rapidly at the beginning of the incubation. Our results suggest that high levels of nitrogen in roots of alder could contribute in slowing the rate of decomposition by allowing the formation of nitrogen-lignin derivatives and low levels of nitrogen in roots of poplar may limit the growth of microorganisms and the rate of root decomposition. A multiple regression was developed using initial nitrogen, lignin concentration and the ratio of lignin to nitrogen to produce an index of the rate of root decomposition. The correlation between the index values and the percentage of residual root mass was significant (r=0.98, p〈0.01).
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