TY - JOUR
T1 - Immobilization and remineralization of N following addition of wheat straw into soil
T2 - Determination of gross N transformation rates by 15N- ammonium isotope dilution technique
AU - Shindo, H.
AU - Nishio, T.
PY - 2005/3
Y1 - 2005/3
N2 - 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.
AB - 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.
KW - N isotope dilution technique
KW - N transformation
KW - Remineralization
KW - Wheat straw incorporation
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U2 - 10.1016/j.soilbio.2004.07.027
DO - 10.1016/j.soilbio.2004.07.027
M3 - Article
AN - SCOPUS:11144327546
VL - 37
SP - 425
EP - 432
JO - Soil Biology and Biochemistry
JF - Soil Biology and Biochemistry
SN - 0038-0717
IS - 3
ER -