| Abstrakt: |
Transformation of organic nitrogen (N) in soil organic matter, and in crop residues, into inorganic forms (defined as N mineralization) allows N to be available to crop plants and/or subject to leaching losses. Estimation of N contribution from crop residues can help finetune fertilizer N application to minimize leaching losses. In potato production systems, wheat, field corn, sweet corn, and alfalfa are used as rotation crops. Nitrogen mineralized from these residues contributes to N supply for the subsequent crop in rotation. In irrigated production systems in the Pacific Northwest, the research indicated that the annual amount of N mineralized from soil organic matter and crop residue accounts for an annual average of 85, 83, 75, 59, and 44 mg·kg1 for sweet corn, alfalfa, field corn, wheat, and potato residues, respectively. The mineralized N during the May through August period accounted for 44 to 58% of total annual N mineralization for the crop residues. This period represents the ideal temperature and soil moisture conditions for maximum mineralization. This is also a period of active plant growth, and plant uptake of mineralized N can be maximized during this period. The in-situ technique adapted in this study provided a convenient method to measure the N mineralization by maintaining the soil moisture and temperature conditions in the incubation columns similar to those in the bulk soil. [ABSTRACT FROM PUBLISHER] |
