Immobilization and remineralization of N following addition of wheat straw into soil: Determination of gross N transformation rates by 15N- ammonium isotope dilution technique

H. Shindo, T. Nishio

Research output: Contribution to journalArticlepeer-review

75 Citations (Scopus)

Abstract

N dynamics in soil where wheat straw was incorporated were investigated by a soil incubation experiment using 15N-labelled nitrate or 15N-labelled wheat straw. The incubated soils were sampled after 7, 28, 54 days from the incorporation of wheat straw, respectively, and gross rates of N transformations including N remineralization and temporal changes in the amount of microbial biomass were determined. Following the addition of wheat straw into soils, rapid decrease of nitrate content in soil and increase of microbial biomass C and N occurred within the first week from onset of the experiment. Both the gross rates of mineralization and immobilization determined by 15N-ammonium isotope dilution technique were remarkably enhanced by the addition of wheat straw, and gradually decreased with time. Remineralization rate of N derived from 15N-labelled nitrate, and mineralization rate of N derived from 15N-labelled wheat straw was estimated by 15N isotope dilution technique using non-labelled ammonium. Remineralization rates of N derived from 15N-labelled nitrate were calculated to be 0.71 mg N kg -1 d -1 after 7 days, 0.55 mg N kg -1 d -1 after 28 days, and 0.29 mg N kg -1 d -1 after 54 days. Nearly 10% of the 15N-labelled N originally contained in the wheat straw was held in the microbial biomass irrespective of the sampling time. The amount of inorganic N in soil which was derived from 15N-labelled wheat straw ranged between 1.93 and 2.37 mg N kg -1. Rates of N transformations in soil with 15N-labelled wheat straw were obtained by assuming that the k value was equal to the 15N abundance of biomass N, and the obtained values were considered to be valid.

Original languageEnglish
Pages (from-to)425-432
Number of pages8
JournalSoil Biology and Biochemistry
Volume37
Issue number3
DOIs
Publication statusPublished - 2005 Mar

Keywords

  • N isotope dilution technique
  • N transformation
  • Remineralization
  • Wheat straw incorporation

ASJC Scopus subject areas

  • Microbiology
  • Soil Science

Fingerprint Dive into the research topics of 'Immobilization and remineralization of N following addition of wheat straw into soil: Determination of gross N transformation rates by <sup>15</sup>N- ammonium isotope dilution technique'. Together they form a unique fingerprint.

Cite this