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Title: Lignin biochemistry and soil N determine crop residue decomposition and soil priming

Author
item Stewart, Catherine
item MOTURI, PRATIBHA - Indian Council Of Agricultural Research (ICAR)
item Follett, Ronald
item Halvorson, Ardell

Submitted to: Biogeochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2015
Publication Date: 4/24/2015
Citation: Stewart, C.E., Moturi, P., Follett, R.F., Halvorson, A.D. 2015. Lignin biochemistry and soil N determine crop residue decomposition and soil priming. Biogeochemistry. 123:335-351. DOI:10.1007.s10533-015-0101.8..

Interpretive Summary: Cropping history can affect soil properties, including available N, but little is known about the interactive effects of residue biochemistry, temperature and cropping history on residue decomposition. A laboratory incubation examined the role of residue biochemistry and temperature on the decomposition rate of five crop residues (corn, sorghum, soybean, sunflower and wheat) in a Weld silt loam soil previously cropped to wheat-fallow [WF] or to corn-millet-wheat [CMW] at either 20 or 30°C.We tracked residue decomposition as 13CO2 and related modeled decomposition parameters to residue biochemistry. The amount of residue decomposed increased from 20 to 30°C by 24.8% in the WF soil and 14.7% in the CMW soil. Final residual NO3 increased from 20 to 30°C by 220% in WF and 190% in the CMW suggesting that increased N availability at higher temperatures plays a crucial role in residue decomposition. Residual soil N will likely moderate the effects of temperature and residue biochemistry in crop residue decomposition in the field and should be characterized in future temperature sensitivity experiments.

Technical Abstract: Cropping history can affect soil properties, including available N, but little is known about the interactive effects of residue biochemistry, temperature and cropping history on residue decomposition. A laboratory incubation examined the role of residue biochemistry and temperature on the decomposition rate of five crop residues [corn (Zea mays L.), sorghum (Sorghum bicolor (L.) Moench), soybean (Glycine max L.), sunflower (Helianthus annuus L.) and wheat (Triticum aestivum L.)] in a Weld silt loam soil previously cropped to wheat-fallow [WF] or to corn-millet-wheat [CMW] at either 20 or 30°C.We tracked residue decomposition as 13CO2 and related modeled decomposition parameters to residue biochemistry. Although residue biochemistry was the primary factor explaining residue decomposition rates of the active (ka) and passive (kp) residue pools, final residual soil NO3 was the best predictor of the size of the active C pool (Ca). The factors explaining ka shifted from total sugars at 20°C to more recalcitrant C sources (neutral detergent fiber and lignin:N) at 30°C, indicating temperature sensitivity. The amount of residue decomposed increased from 20 to 30°C by 24.8% in the WF soil and 14.7% in the CMW soil. Final residual NO3 increased from 20 to 30°C by 220% in WF and 190% in the CMW suggesting that increased N availability at higher temperatures plays a crucial role in residue decomposition. Residual soil N will likely moderate the effects of temperature and residue biochemistry in crop residue decomposition in the field and should be characterized in future temperature sensitivity experiments.