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Factors Affecting Nitrogen Immobilization in Soil as Estimated by Simulation Models
Author(s) -
Hadas Aviva,
Feigenbaum Sala,
Molina J. A. E.,
Clapp C. E.
Publication year - 1992
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1992.03615995005600050024x
Subject(s) - soil water , organic matter , nitrification , chemistry , soil organic matter , nitrate , environmental chemistry , nitrogen , biomass (ecology) , mineralization (soil science) , soil science , agronomy , environmental science , biology , organic chemistry
Factors that control immobilization of inorganic N in soils not amended with organic C‐rich materials have not been fully established. Different N flow schemes for N immobilization were tested by comparing the kinetics of CO 2 evolution, NH + 4 ‐N, NO ‐ 3 ‐N, inorganic 15 N, and organic 15 N excess, measured in soils incubated with 200 mg kg −1 of 15 N‐labeled NH + 4 ‐N, with data simulated by the computer model NCSOIL structured to representseveral pathways of C and N turnover. Estimates of those parameters most likely to induce or enhance N immobilization, namely the mineralizable soil organic matter content, its C/N ratio, and the efficiency with which C is assimilated by the soil microbial biomass were obtained by optimization. Cumulative N immobilization was up to 10% of the N added and was greater when NH + 4 was added to dry soils than when added to preincubated soils. The immobilization was primarily due to the microbial biomass drawing N from the inorganic pool, rather than utilizing N directly from the decomposing soil organic matter. Nitrate formed by nitrification seemed to have also been immobilized. A microbial efficiency factor of 0.4 and a C/N ratio of 20 or more for mineralizable soil organic matter were needed to account for the observed rate of N immobilization.