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Estimating Gross Nitrogen Mineralization and Immobilization Rates in Anaerobic and Aerobic Soil Suspensions
Author(s) -
Smith C. J.,
Chalk P. M.,
Crawford D. M.,
Wood J. T.
Publication year - 1994
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/sssaj1994.03615995005800060011x
Subject(s) - anaerobic exercise , mineralization (soil science) , remineralisation , chemistry , incubation , nitrogen , environmental chemistry , rice straw , zoology , soil science , straw , mineralogy , environmental science , inorganic chemistry , fluoride , biology , biochemistry , physiology , organic chemistry
Zero‐order models for estimating gross rates of N mineralization ( m ) and immobilization ( i ) of NH + 4 in soils were characterized by expressing the analytical solutions in a standard format. Three models of m were identified out of seven evaluated. One model was based on the solution of differential equations, and two on arithmetic mean data of ratios of labeled and total NH + 4 pools. Data from well‐mixed anaerobic and aerobic soil suspensions amended with rice straw and labeled with ( 15 NH 4 ) 2 SO 4 were used to compare the three models of m and four models of i for 56 d, with measurements every 7 d. Estimated rates of m declined during incubation, particularly during the first 21 d. Correction of m for remineralization of immobilized 15 N in the anaerobic system using the total organic N pool (OT) had little effect, but the correction was more pronounced when the estimated active organic N pool (OT*) was used. Remineralization did not account for the observed decline in m during anaerobic incubation. Numerical modeling and nonlinear parameter estimation were also used to estimate m and i , with values being similar to analytical estimates for Days 0 to 7 ( m ) and Days 7 to 14 ( i ). The OT* comprised 10 to 11% of OT in both suspensions. Estimates of OT* were derived from the numerical analysis (anaerobic), or by assuming approximate isotopic equilibrium between the NH + 4 (anaerobic) or NO − 3 (aerobic) pools and the organic N pool following remineralization of immobilized isotope.