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Relationship Between Microbial Biomass Nitrogen and a Nitrogen Availability Index
Author(s) -
Myrold David D.
Publication year - 1987
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/sssaj1987.03615995005100040040x
Subject(s) - incubation , mineralization (soil science) , fumigation , nitrogen , nitrogen cycle , chloroform , soil water , chemistry , anaerobic exercise , environmental chemistry , biomass (ecology) , agronomy , biology , ecology , chromatography , biochemistry , organic chemistry , physiology
This study examined the microbiological basis for the anaerobic N mineralization assay, a technique that has been widely used in studies of N availability in forest soils. It was hypothesized that N mineralized using the anaerobic incubation method came mainly from killed microbial cells, similar to the flush of N obtained from the chloroform fumigation‐incubation method for determining microbial biomass. Soil samples, representative of a wide range of forest types in Oregon, were analyzed for the amount of NH + 4 released after a 7‐d anaerobic incubation and by the standard chloroform fumigation‐incubation method. A second experiment was done using the same soils treated with 15 NH 4 Cl, and the isotopic labeling of the NH + 4 released by both methods was determined. There was a highly significant correlation between both the amount and atom % 15 N of NH + 4 released by the two procedures (r 2 = 0.81 and 0.82, respectively). These results suggest that the anaerobic N mineralization assay measures N released primarily from the microbial biomass.