Modeling Tall Fescue Cultivar Response to Applied Nitrogen

Abstract

AbstractModels can be used to estimate yields and nutrient utilization by forage grasses. The objective of this study was to model response of three cultivars of tall fescue (Festuca arundinacea Schreb.) to applied N over a 3‐yr period at Watkinsville, GA. The procedure uses analysis of variance to evaluate linear parameter A and the exponential parameters b and c for the logistic equation. It was shown that yields could be averaged across years and that all differences among cultivars could be assigned to the b (intercept) parameter. ‘All‐Triumph’ proved to be more efficient at converting soil N to dry matter without applied N than either ‘Johnstone’ or ‘Kentucky 31’ cultivars. Endophyte (Acremonium coenophialum Morgan‐Jones & Gams) infection did not affect dry matter response relationships of Kentucky 31. Maximum incremental conversion of applied N to dry matter occurred at N = 125 kg ha−1, where plant N utilization was ≈80%. The logistic model provides a very useful tool for evaluating response of tall fescue cultivars to applied N.