Influence of Soil, Management, and Climatic Factors on the Yield Response by Corn (Zea mays L.) to N, P, and K Fertilizer
1970
Voss, R. E. | Hanway, J. J. | Fuller, W. A.
Quantitative evaluations of applied fertility, indigenous soil properties, management, and weather variables in field experiments were all necessary to develop a satisfactory relationship between corn grain yield and the responsible factors. Experimental sites were selected that provided a sufficiently wide range in each uncontrolled variable to permit inferences concerning the entire Marshall and Monona soil areas. At each site, 19 different N-P-K fertilizer combinations were applied in a composite type design, with 6 of the treatments replicated. Each plot was characterized, for soil test N, P, K, and pH, stand level, and barrenness. Variables evaluated on a site basis were past cropping, subsoil fertility, planting date, soil yield potential, and soil moisture stress, A multiple-regression equation for yield, fitting data from 575 plots, contained 40 terms and achieved an R₂ of 0.80. It contained interactions among applied fertility, indigenous fertility, management, and climatic factors. Response to applied N was influenced most by past cropping and soil moisture stress. Response to applied P was not influenced by environmental factors as much as was response to N, but “available” soil P, soil N, and soil moisture stress influenced P response. These soils, which rate “medium” or “high” in exchangeable K, responded only slightly and negatively to applied K fertilizer. Significant interactions were measured between soil moisture and plant population and between soil moisture and planting date. The necessity lor this type of field experimentation is discussed. Methods of interpretation and practical applications of yield prediction equations are suggested and exemplified.
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