Residue Harvest Effects on Irrigated, No-Till Corn Yield and Nitrogen Response

Crop residue harvest occurs on about 40% of Nebraska's 3,700,000 ha of corn (Zea mays L.) land, primarily for feeding of beef cattle. Immobilization of applied N is expected to be less with residue harvest due to reduced microbial activity for digestion of high C/N ratio organic material. Residue reduction may affect subsequent crop yield and response to applied N. Field research was conducted at three locations over 2 yr in eastern Nebraska for irrigated, no-till corn following corn to determine residue harvest effects on yield and the economically optimal nitrogen rate (EONR). Study sites had deep silt loam or silty clay loam soil with good water infiltration and plant-available water holding capacity. Mean aboveground biomass N content, applied N recovery efficiency, and grain yield were 22, 43, and 20% higher with >75% residue removal compared with no residue removal. Agronomic efficiency of applied N use was not consistently affected. The residue removal effects were oft en greater in the third compared with second year of continuous corn. The residue removal effect on EONR was not consistent over site-years, and the mean reduction in EONR with residue removal was between 10 and 20 kg ha(-1). While removal of some corn residue is expected to result in higher yield of the following corn crop, reduction in applied N need cannot be well predicted before planting.