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.