REDUCING NITRATE LOSSES FROM AGRICULTURAL FIELDS WITH SUBSURFACE DRAINAGE
Title: Aerobic decomposition of crop residues improves N availability and grain yield for three rice soils of the Mekong Delta, Vietnam: A screenhouse study
| Trang, T - CAN THO UNIV., VIETNAM |
| Guong, V - CAN THO UNIV., VIETNAM |
| Vien, D - CAN THO UNIV., VIETNAM |
| Dong, N - CAM THO UNIV., VIETNAM |
| Merckx, R - KATHOLIEKE UNIV., BELGIUM |
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 8, 2007
Publication Date: November 8, 2007
Citation: Trang, T.T., Guong, V.T., Olk, D.C., Vien, D.M., Dong, N.M., Merckx, R. 2007. Aerobic decomposition of crop residues improves N availability and grain yield for three rice soils of the Mekong Delta, Vietnam: A screenhouse study [CD-ROM]. In: ASA-CSSA-SSSA Annual Meeting Abstracts, Nov. 4-8, 2007, New Orleans, LA.
In the Mekong Delta of Vietnam, rice (Oryza sativa, L.) is usually planted two to three times annually. Limited evidence elsewhere suggests that rice crop uptake of soil nitrogen (N) under such intensive cropping can be increased by replacing the customary anaerobic decomposition of crop residues with aerobic decomposition. In this screenhouse study, crop residues were incorporated into three potted Delta soils and allowed to decompose for two to four weeks under either aerobic or anaerobic conditions. In the following flooded rice crop, grain yield increased for the three soils by 11, 13, and 37% with two-week drying compared to anaerobic decomposition and by 19, 35, and 69% with four-week drying. Crop N uptake provided analogous increases: 14, 31, and 63% for two-week drying and 3, 48, and 96% with four-week drying. The increase in N uptake involved mostly soil N, not fertilizer N. The quantities of labile humic acid fractions that were extracted from the three soils were 6 to 31% less with aerobic decomposition than with anaerobic decomposition. These results suggest that aerobic decomposition of crop residues promoted mineralization and crop uptake of soil N.