Yield of Corn Grain as Affected by Fertilizer Rates and Environmental Factors1

Abstract

AbstractEighteen experiments were conducted on the Clarion, Nicollet, and Webster soil series in Iowa to determine which selected measureable soil, management and weather factors affect the yield and response of corn grain to applied N, P, and K in multirate experiments and to quantify these combined effects through multiple regression analyses. The unfertilized plot grain yields were related to soil test values for N. P. K. and pH; time of planting; yielding ability of the corn hybrids planted; plant population and weather as characterized by a stress day criterion based on moisture depletion of the rooting zone. Soil pH and soil sources of N, P, and K; time of planting; plant population; yielding ability of the hybrids; and the stress days in the 5 weeks following planting affected the yield response to applied nutrients as indicated by multiple regression analyses.Methods for determining which factors affected yield and response to applied nutrients are described. The effect of a measurable uncontrolled factor on the response to an applied nutrient was determined by examining the slopes of the n‐dimensional yield surface.