Journal article
Nitrogen immobilization and mineralization during initial decomposition of 15N-labelled pea and barley residues
The immobilization and mineralization of N following plant residue incorporation were studied in a sandy loam soil using N-15-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 N-15 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.
Language: | English |
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Publisher: | Springer-Verlag |
Year: | 1997 |
Pages: | 39-44 |
ISSN: | 14320789 and 01782762 |
Types: | Journal article |
DOI: | 10.1007/BF01420218 |