A logistic equation for yield response of forage grass to nitrogen

Abstract

A logistic equation was used to relate dry matter yield to applied nitrogen for Pensacola bahiagrass. Data from Georgia with 5 N rates and for 5 years were used. Procedures were outlined for evaluation of the 3 parameters. The 2nd order Newton‐Raphson method was used to optimize parameters. The error matrix provided estimates of the standard error for each parameter, which were used for sensitivity analysis. Probability contours were constructed for the nonlinear parameters at 75% and 95% confidence levels. Finally, it was shown by analysis of variance that each parameter had a common value for all 5 years of data. Additional work is underway to relate model parameters to water availability and harvest interval.