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Crop Residue Type and Placement Effects on Denitrification and Mineralization
Author(s) -
Aulakh M. S.,
Walters D. T.,
Doran J. W.,
Francis D. D.,
Mosier A. R.
Publication year - 1991
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/sssaj1991.03615995005500040022x
Subject(s) - loam , vicia villosa , denitrification , crop residue , agronomy , chemistry , mineralization (soil science) , residue (chemistry) , soil water , nitrogen , environmental science , biology , soil science , cover crop , agriculture , ecology , biochemistry , organic chemistry
Nutrient release from legume and cereal crop residue is important to N crycling and the success of conservation and sustainable farming systems. Residue type, placement, and degree of incorporation, and soil water regimes largely control availability and loss of soil N and were evaluated in the laboratory. Four residues, i.e., vetch ( Vicia villosa Roth.), soybean ( Glycine max [L.] Merr.), corn ( Zea mays L.), and wheat ( Triticum aestivum L.) having C/N ratios ranging from 8 to 82 were applied on the soil surface or incorporated in repacked cores of a Nicollet loam (fine‐loamy, mixed, mesic Aquic Hapludoll) and incubated for 17 or 35 d at 60 and 90% water‐filled pore space (WFPS) with enriched 15 N‐NO 3 (76.7%). Denitrification losses from all treatments were negligible at 60% WFPS. At 90% WFPS, total denitrification losses from residue‐incorporated soils represented 87 to 127% of the initial soil NO 3 level (80.5 mg N kg −1 ); losses increased with decreasing residue C/N ratio. Denitrification was greatest during the first 8 d, as was CO 2 evolution. Initial denitrification with surface‐placed residues was less than with incorporated residues, but cumulative losses over 35 d did not differ significantly. Substantial N immobilization occurred with incorporated or surface‐placed wheat, corn, and soybean residue with wide C/N ratios at 60% WFPS, whereas, with low‐C/N‐ratio vetch, significant mineralization occurred. After 35 d, 51 and 36% of N in incorporated and surface‐placed vetch residue, respectively, was mineralized. Residue C/N ratio was inversely related to initial rates of residue decomposition, and effects of residue type and placement and soil water on denitrification and mineralization were most important during early (8‐10 d) decomposition.