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This article in SSSAJ

  1. Vol. 62 No. 3, p. 750-755
     
    Received: Jan 6, 1997
    Published: May, 1998


    * Corresponding author(s): gilmour@comp.uark.edu
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doi:10.2136/sssaj1998.03615995006200030030x

Kinetics of Crop Residue Decomposition: Variability among Crops and Years

  1. John T. Gilmour ,
  2. Richard J. Norman,
  3. Andy Mauromoustakos and
  4. Paula M. Gale
  1. Dep. of Agronomy, Plant Science 115, Univ. of Arkansas, Fayetteville, AR 72701
    Agricultural Statistics, Univ. of Arkansas, Fayetteville, AR 72701
    School of Agriculture and Natural Resources, Univ. of Tennessee, Martin, TN 38238

Abstract

Abstract

A kinetic description of crop residue decomposition makes assessment of the global C cycle and nutrient cycling possible for a wide variety of crop production systems. It was the objective of this study to compare decomposition kinetics of soybean [Glycine max (L.) Merr.], rice (Oryza sativa L.) and grain sorghum [Sorghum bicolor (L.) Moench.] residues for 3 yr to determine if variability among years was similar to that among crops. Crop residues were incorporated into a Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualf) soil and incubated at 25°C under optimum soil moisture for 54 to 66 d. Initial (0–2-wk) decomposition was related to crop residue organic N and C/N ratio, while subsequent decomposition was not related to these factors. Decomposition data were evaluated using first-order kinetics and sequential and simultaneous decomposition models. As a result of the variability among crops and years, which was not related to residue characteristics (organic N or C/N ratio), it was concluded that mean estimates of rate constants and the rapid fraction would provide a reasonable estimate of crop residue decomposition for a variety of crops using either decomposition model. For the sequential model, mean rapid- and slow-fraction rate constants were 0.025 and 0.0091 d−1, respectively, while the rapid fraction was 31%. Parallel values for the simultaneous model were 0.21 and 0.0080 d−1 and 20%.

Published with the approval of the director, Arkansas Agric. Exp. Stn., manuscript no. 97001.

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