Chloroform fumigation and the release of soil nitrogen: a rapid direct extraction method to measure microbial biomass nitrogen in soil

A - Papers appearing in refereed journals

Brookes, P. C., Landman, A., Pruden, G. and Jenkinson, D. S. 1985. Chloroform fumigation and the release of soil nitrogen: a rapid direct extraction method to measure microbial biomass nitrogen in soil. Soil Biology and Biochemistry. 17 (6), pp. 837-842.

AuthorsBrookes, P. C., Landman, A., Pruden, G. and Jenkinson, D. S.
Abstract

A new “direct extraction” method for measuring soil microbial biomass nitrogen (biomass N) is described. The new method (fumigation-extraction) is based on CHC13 fumigation, followed by immediate extraction with 0.5 M K2SO4 and measurement of total N released by CHC13 in the soil extracts. The amounts of NH4-N and total N extracted by K2SO4 immediately after fumigation increased with fumigation time up to 5 days. Total N released by CHC13 after 1 day fumigation (1 day CHC13-N) and after 5 days fumigation (5 day CHC13-N) were positively correlated with the flush of mineral N (FN) in 37 soils that had been fumigated, the fumigant removed and the soils incubated for 10 days (fumigation-incubation). The regression equations were 1 day CHC13-N = (0.79 ± 0.022) FN and 5 day CHC13-N = (1.01 ± 0.027) FN, both regressions accounting for 92% of the variance in the data.In field soils previously treated with 15N-labelled fertilizer, the amounts of labelled N, measured after fumigation-extraction, were very similar to the amounts of labelled N mineralized during fumigation-incubation; both were about 4 times as heavily labelled as the soil N as a whole. These results suggest that fumigation-extraction and fumigation-incubation both measure the same fraction of the soil organic N (probably the cytoplasmic component of the soil microbial biomass) and that measurement of the total N released by CHC13 fumigation for 24 h provides a rapid method for measuring biomass N.

KeywordsRRES175; 175_Biochemistry; 175_Soil science
Year of Publication1985
JournalSoil Biology and Biochemistry
Journal citation17 (6), pp. 837-842
Digital Object Identifier (DOI)doi:10.1016/0038-0717(85)90144-0
Open accessPublished as non-open access
Publication process dates
Accepted14 May 1985
PublisherElsevier
Copyright licensePublisher copyright
ISSN0038-0717

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