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  • 1
    Electronic Resource
    Electronic Resource
    Labelling of animal manure nitrogen with15N (1994)
    Springer
    Plant and soil 162 (1994), S. 31-37 
    Details
    ISSN: 1573-5036
    Keywords: homogeneity of labelling ; mineralization ; mobile nylon bag ; ryegrass hay ; sheep manure ; water-soluble N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A sheep was fed on15N-labelled ryegrass hay during a period of 9 days in order to obtain15N-labelled manure. After 9 days of feeding, the total N in faeces contained 3.70 atom %15N excess, which was equivalent to 82% of the15N enrichment of the hay N. The easily-decomposable fraction of the faecal N was less labelled (2.89 atom %15N excess) than the slowly-decomposable fraction. The15N enrichment of mineralized faecal N did not change significantly during 32 weeks of incubation in sand. About 25% of the faecal N was water-soluble. This N had a higher15N enrichment than the total faecal N, indicating that a part of the water-soluble N was indigestible feed N. The faeces contained only small amounts of NH 4 + -N, which had a15N enrichment similar to the15N enrichment of N mineralized during incubation in sand. It is suggested that the labelled faecal N obtained after a few days of feeding on labelled feed could be divided in two N pools: A decomposable N fraction (about 60%) with a15N enrichment similar to the enrichment of N mineralized in sand (2.89 ± 0.09 atom %15N excess), and a very slowly-decomposable N fraction (about 40%) with a15N enrichment similar to that of the feed (4.52 atom %15N excess).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01416087
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  • 2
    Electronic Resource
    Electronic Resource
    The fate of15N-labelled organic nitrogen in sheep manure applied to soils of different texture under field conditions (1994)
    Springer
    Plant and soil 162 (1994), S. 39-47 
    Details
    ISSN: 1573-5036
    Keywords: animal manure ; immobilization ; leaching ; mineralization ; N-balance ; ryegrass ; spring barley
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The fate of nitrogen from15N-labelled sheep manure and ammonium sulfate in small lysimeters and plots in the field was studied during two growth seasons. In April 1991,15N-labelled sheep faeces (87 kg N ha−1) plus unlabelled (NH4)2SO4 (90 kg N ha−1), and (15NH4)2SO4 (90 kg N ha−1) were each applied to three soils; soil 1 (100% soil + 0% quartz sand), soil 2 (50% soil + 50% quartz sand) and soil 3 (25% soil + 75% quartz sand). The lysimeters were cropped with spring barley (Hordeum vulgare L.) and undersown ryegrass (Lolium perenne L.). The barley crop recovered 16–17% of the labelled manure N and 56% of the labelled (NH4)2SO4-N. After 18 months 30% of the labelled manure N and 65% of the labelled (NH4)2SO4-N were accumulated in barley, the succeeding ryegrass crop and in leachate collected below 45 cm of soil, irrespective of the soil-sand mixture. Calculating the barley uptake of manure N by difference of N uptake between manured and unmanured soils, indicated that 4%, 10% and 14% of the applied manure N was recovered in barley grown on soil-sand mixtures with 16%, 8% and 4% clay, respectively. The results indicated that the mineralization of labelled manure N was similar in the three soil-sand mixtures, but that the manure caused a higher immobilization of unlabelled ammonium-N in the soil with the highest clay content. Some of the immobilized N apparently was remineralized during the autumn and the subsequent growth season. After 18 months, 11–19% of the labelled manure N was found in the subsoil (10–45 cm) of the lysimeters, most of this labelled N probably transported to depth as organic forms by leaching or through the activities of soil fauna. In unplanted soils 67–74% of the labelled manure N was recovered in organic form in the 0–10 cm soil layer after 4 months, declining to 55–64% after 18 months. The lowest recovery of labelled N in top-soil was found in the soil-sand mixture with the lowest clay content. The mass balance of15N showed that the total recovery of labelled N was close to 100%. Thus, no significant gaseous losses of labelled N occurred during the experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01416088
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  • 3
    Electronic Resource
    Electronic Resource
    Seasonal patterns of growth and nitrogen fixation in field-grown pea (1987)
    Springer
    Plant and soil 101 (1987), S. 29-37 
    Details
    ISSN: 1573-5036
    Keywords: assimilate partitioning ; growth analysis ; leaf area ; nitrate ; nitrogen fixation ; 15N isotope dilution ; pea ; Pisum sativum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The seasonal patterns of growth and symbiotic N2 fixation under field conditions were studied by growth analysis and use of15N-labelled fertilizer in a determinate pea cultivar (Pisum sativum L.) grown for harvest at the dry seed stage. The patterns of fertilizer N-uptake were almost identical in pea and barley (the non-fixing reference crop), but more fertilizer-N was recovered in barley than in pea. The estimated rate of N2 fixation in pea gradually increased during the pre-flowering and flowering growth stages and reached a maximum of 10 kg N fixed per ha per day nine to ten weeks after seedling emergence. This was the time of early pod-development (flat pod growth stage) and also the time for maximum crop growth rate and maximum green leaf area index. A steep drop in N2 fixation rate occurred during the following week. This drop was simultaneous with lodging of the crop, pod-filling (round pod growth stage) and the initiation of mobilization of nitrogen from vegetative organs. The application of fertilizer-N inhibited the rate of N2 fixation only during that period of growth, when the main part of fertilizer-N was taken up and shortly after. Total accumulation of fixed nitrogen was estimated to be 244, 238 and 213 kg N ha−1 in pea supplied with nil, 25 or 50 kg NO 3 − −N ha−1, respectively. About one-fourth of total N2 fixation was carried out during preflowering, one fourth during the two weeks of flowering and the remainder during post-flowering. About 55% of the amount of N present in pods at maturity was estimated to be derived from mobilization of N from vegetative organs. “Starter” N (25 or 50 kg NO 3 − −N ha−1) did not significantly influence either dry matter and nitrogen accumulation or the development of leaf area. Neither root length and root biomass determined 8 weeks after seedling emergence nor the yield of seed dry matter and nitrogen at maturity were influenced by fertilizer application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02371027
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  • 4
    Electronic Resource
    Electronic Resource
    Symbiotic N2-fixation by the cover crop Pueraria phaseoloides as influenced by litter mineralization (1995)
    Springer
    Plant and soil 177 (1995), S. 1-10 
    Details
    ISSN: 1573-5036
    Keywords: cross-labeling ; litter mineralization ; 15N isotope dilution ; Pueraria phaseoloides ; symbiotic N2-fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The perennial legume Pueraria phaseoloides is widely used as a cover crop in rubber and oil palm plantations. However, very little knowledge exists on the effect of litter mineralization from P. phaseoloides on its symbiotic N2-fixation. The contribution from symbiotic N2-fixation (Ndfa) and litter N (Ndfl) to total plant N in P. phaseoloides was determined in a pot experiment using a 15N cross-labeling technique. For determination of N2-fixation the non-fixing plant Axonopus compressus was used as a reference. The experiment was carried out in a growth chamber during 9 weeks with a sandy soil and 4 rates of ground litter (C/N=16,2.8% N). P. phaseoloides plants supplied with the highest amount of litter produced 26% more dry matter and fixed 23% more N than plants grown in soil with no litter application, but the percentage of Ndfa decreased slightly, but significantly, from 87 to 84%. The litter N uptake was directly proportional to the rate of application and constituted 10% of total plant N at the highest application rate. Additionally, a positive correlation was found between litter N uptake and the amount of fixed N2. The total recovery of litter N in plants averaged 26% at harvest (shoot + root) and was not affected by the quantity added. A parallel incubation experiment also showed that, as an average of all litter levels, 26% of the litter N was present in the inorganic N pool. The amounts of fertilizer and soil N taken up by plants decreased with litter application, probably due to microbial immobilization and denitrification. It is concluded that, within the litter levels studied, litter mineralization will result in a higher amount of N2-fixed by P. phaseoloides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010332
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