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  • 1
    Electronic Resource
    Electronic Resource
    Nitrogen immobilization and mineralization during initial decomposition of 15N-labelled pea and barley residues (1996)
    Springer
    Biology and fertility of soils 24 (1996), S. 39-44 
    Details
    ISSN: 1432-0789
    Keywords: Key words Immobilization ; Mineralization ; 15N-labelled crop residues ; Residue quality ; Soil microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The immobilization and mineralization of N following plant residue incorporation were studied in a sandy loam soil using 15N-labelled field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) straw. Both crop residues caused a net immobilization of soil-derived inorganic N during the complete incubation period of 84 days. The maximum rate of N immobilization was found to 12 and 18 mg soil-derived N g–1 added C after incorporation of pea and barley residues, respectively. After 7 days of incubation, 21% of the pea and 17% of the barley residue N were assimilated by the soil microbial biomass. A comparison of the 15N enrichments of the soil organic N and the newly formed biomass N pools indicated that either residue N may have been assimilated directly by the microbial biomass without entering the soil inorganic N pool or the biomass had a higher preference for mineralized ammonium than for soil-derived nitrate already present in the soil. In the barley residue treatment, the microbial biomass N was apparently stabilized to a higher degree than the biomass N in the pea residue treatment, which declined during the incubation period. This was probably due to N-deficiency delaying the decomposition of the barley residue. The net mineralization of residue-derived N was 2% in the barley and 22% in the pea residue treatment after 84 days of incubation. The results demonstrated that even if crop residues have a relative low C/N ratio (15), transient immobilization of soil N in the microbial biomass may contribute to improved conservation of soil N sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420218
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  • 2
    Electronic Resource
    Electronic Resource
    Nitrogen immobilization and mineralization during initial decomposition of15N-labelled pea and barley residues (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 39-44 
    Details
    ISSN: 1432-0789
    Keywords: Immobilization ; Mineralization ; 15N-labelled crop residues ; Residue quality ; Soil microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The immobilization and mineralization of N following plant residue incorporation were studied in a sandy loam soil using15N-labelled field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) straw. Both crop residues caused a net immobilization of soil-derived inorganic N during the complete incubation period of 84 days. The maximum rate of N immobilization was found to 12 and 18 mg soil-derived N g−1 added C after incorporation of pea and barley residues, respectively. After 7 days of incubation, 21% of the pea and 17% of the barley residue N were assimilated by the soil microbial biomass. A comparison of the15N enrichments of the soil organic N and the newly formed biomass N pools indicated that either residue N may have been assimilated directly by the microbial biomass without entering the soil inorganic N pool or the biomass had a higher preference for mineralized ammonium than for soil-derived nitrate already present in the soil. In the barley residue treatment, the microbial biomass N was apparently stabilized to a higher degree than the biomass N in the pea residue treatment, which declined during the incubation period. This was probably due to N-deficiency delaying the decomposition of the barley residue. The net mineralization of residue-derived N was 2% in the barley and 22% in the pea residue treatment after 84 days of incubation. The results demonstrated that even if crop residues have a relative low C/N ratio (15), transient immobilization of soil N in the microbial biomass may contribute to improved conservation of soil N sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420218
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    Paper (German National Licenses)
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  • 3
    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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    Paper (German National Licenses)
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  • 4
    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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    Paper (German National Licenses)
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