Determination of in situ KN by the chloroform fumigation-incubation method and mineralization of biomass N under anaerobic conditions

F. Azam, R. L. Mulvaney, F. J. Stevenson

Research output: Contribution to journalArticlepeer-review

Abstract

A silt loam soil from Pakistan was incubated at 30°C with increasing levels (67, 133, 200, 267 and 333 μg N g-1 soil) of15N-labelled (NH4)2SO4 and glucose (C/N ratio of 30 for all additions). At a stage when all of the applied15N was immobilized (transformed into microbial biomass), moist soil samples were subjected to the chloroform fumigation-incubation method (CFIM) for determination of KN and microbial biomass. Mineralization of biomass derived from the applied15N and the native soil N was studied under anaerobic conditions. In situ values of KN varied from 0.19 to 0.42 and increased with increasing levels of amendment (N + glucose). From 10 to 18% of the native soil N was found as microbial biomass. Anaerobic incubation of the soils resulted in the mineralization (determined as NH4+) of 15.08 to 29.23% of the biomass15N at different levels of amendment; 2.90 to 4.43% of the native soil N was mineralized. From 70 to 90% of the N mineralized from native soil N was derived from microbial biomass; the rest was attributed to non-biomass N.

Original languageEnglish (US)
Pages (from-to)87-93
Number of pages7
JournalPlant and Soil
Volume111
Issue number1
DOIs
StatePublished - Sep 1 1988

Keywords

  • N immobilization
  • N mineralization
  • anaerobic incubation
  • chloroform fumigation
  • microbial biomass

ASJC Scopus subject areas

  • Soil Science
  • Plant Science

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