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Determination of Microbial Biomass and Nitrogen Mineralization following Rewetting of Dried Soil
Author(s) -
Franzluebbers A. J.,
Haney R. L.,
Hons F. M.,
Zuberer D. A.
Publication year - 1996
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/sssaj1996.03615995006000040025x
Subject(s) - mineralization (soil science) , loam , fumigation , nitrogen cycle , soil water , environmental chemistry , chemistry , environmental science , soil respiration , soil test , incubation , nitrogen , agronomy , soil science , biology , biochemistry , organic chemistry
Routine soil testing procedures that are rapid and precise are needed to evaluate agricultural surface soils for their potential to mineralize C and N. Our objectives were to determine the optimum preincubation time after rewetting of dried soil for estimating soil microbial biomass (SMB) and to identify a quick, reliable biochemical predictor of soil N mineralization potential. Biochemical determinations of SMB were screened on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) having five levels of soil organic C (SOC) as a result of long‐term management. Determinations used (i) field‐moist soil and (ii) soil that was air dried, rewetted, and preincubated for 0.2, 1, 3, 6, 10, and 15 d. Biochemical determinations included arginine ammonification, substrate‐induced respiration (SIR), cumulative C and net N mineralization, and SMBC using the chloroform fumigation‐incubation (CFI) method. Preincubation periods of 1 and 15 d prior to fumigation gave estimates of SMBC using CFI most similar to those determined on field‐moist soil. Arginine ammonification and SIR determinations on dried soil were highly variable, making longer preincubation periods necessary. Carbon mineralization during all preincubation periods was highly correlated to (i) SMBC using CFI determined on field‐moist and dried soil with all preincubation periods and (ii) net N mineralization during 21 d for the Weswood soil, as well as for seven additional soil series each having five to eight levels of SOC. The CO 2 ‐C evolved during the first day after rewetting of dried soil is recommended for rapid estimation of SMBC and potential N mineralization because of its simplicity and precision.