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Estimation of Yield and Nitrogen Removal by Corn

Agricultural Engineering Dep., Univ. of Florida, Gainesville, FL 32611-0570

Eugene J. Kamprath

Soil Science Dep., North Carolina State Univ., Raleigh, NC 27695-7619

^* Corresponding author.

A wide variety of mathematical models have been used to relate crop production to management factors such as applied N and water availability. These include power functions and exponential functions. The objective of this analysis was to use an extended logistic model to relate dry :matter yields and plant N removal to applied N for corn (Zea mays L.) for three soils in North Carolina. In this model, response of both dry matter yield and plant N removal to applied N were described by logistic equations. Plant N concentration was then related to applied N by the ratio of these logistic equations. Model parameters were estimated by nonlinear regression. Analysis of variance showed that the N response coefficient c was common for dry matter yield and plant N removal for each soil. Overall correlation coefficients of yield and plant N removal with applied N were very high for all three soils (R> 0.99). It was shown that 50% of the total dry matter and 80% of total plant N were contained in the grain at all applied N levels. Maximum potential grain yield of 25.9 Mg ha^–1 agreed closely with an estimate in the literature of 26.5 Mg ha^–1 (500 bushels acre^–1). Dependence of plant N concentration on plant N removal was shown to follow a linear relationship. The present model provides a rational basis for coupling of dry matter yield and plant N removal in response to applied N. It can be used in design and management decisions related to agricultural production and environmental quality.

Received for publication September 10, 1993.