ESTIMATION OF CORN RESPONSE TO WATER AND APPLIED NITROGEN

The objective of this work was to use the logistic equation to relate grain and total plant yield of corn [Zea mays (L.)] to water and appli ed N. Data from field studies in Florida and Georgia were used in the analysis. Nonlinear correlation coefficients R > 0.98 were obtained. V ariation among hybrids, between plant components (grain and total plan t), and among years (rainfall) was accounted for in the linear model p arameter A, with constant exponential parameters b and c. The linear m odel parameter A exhibited linear dependence on seasonal rainfall for corn in Georgia. Data from a third study in Florida showed linear depe ndence of A upon seasonal rainfall plus irrigation for total amounts u p to 70 cm. This model provides a convenient tool for relating corn yi elds to applied N and available water, with the response function sepa rating into the product of a term depending upon water and another dep ending upon applied N. The equation is mathematically well-behaved and is easy to use on a pocket calculator by managers and engineers.