Nutrient uptake of corn in relation to water inputs, corn heat units, fertilizer, and plant populations

Abstract

Optimization of plant populations, of fertilizer rates and of irrigation are management options that can affect grain yield and quality. The efficiency of these management practices may be dependent upon meteorological conditions. The objective of this study was to quantify grain N, P, and K concentrations and uptake as a function of the com heat units (CHU) and seasonal water inputs. A field experiment was conducted on a Chicot sandy clay‐loam soil (fine‐loamy, mixed, frigid, Typic Hapludalf) in Quebec from 1984 to 1989. Empirical equations for N, P and K concentrations in grain and their uptake were developed under each combination of two plant populations (65,000 and 90,000 plants/ha) and two fertilizer rates (170–44–141) and 400–132–332 kg/ha as N‐P‐K). Grain‐N concentration was found to be a function of grain yields and CHU values. No quantitative dilution effect due to increasing grain yields was found for grain‐P and ‐K concentrations. Models for grain N, P, and K concentrations and their uptake in relation to CHU and water inputs during the growing season were established under varied management practices. Corn heat units were a key factor affecting macro‐nutrient concentrations in grain and their uptake by corn in Quebec.

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