Nitrogen mineralization from different crop residues in the Pacific Northwest irrigated potato cropping systems
2005
Alva, A.K. | Collins, H.P. | Boge, W.L. | Boydston, R.A.
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•kg-1 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.
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