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Kinetics of Crop Residue Decomposition: Variability among Crops and Years
Author(s) -
Gilmour John T.,
Norman Richard J.,
Mauromoustakos Andy,
Gale Paula M.
Publication year - 1998
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1998.03615995006200030030x
Subject(s) - crop residue , sorghum , loam , agronomy , residue (chemistry) , decomposition , crop , chemistry , mathematics , soil water , environmental science , soil science , agriculture , biology , ecology , organic chemistry
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%.