Model Analysis of Crabgrass Response to Applied Nitrogen

Abstract

The extended logistic model of crop response to applied nutrients provides quantitative coupling of seasonal dry matter (Y), plant N uptake (N u ), and plant N concentration (N c ) with applied nutrient (N). It predicts a hyperbolic relationship between Y and N c with N u . Analysis of data from numerous studies has confirmed the model. In this article the model was applied to data for crabgrass (Digitaria sanguinalis) grown at Ardmore, OK. Results showed that single applications of nitrogen provided greater yields and plant N uptake over split applications. The difference was accounted for in the linear parameters for yield (A) and for plant N uptake (A n ). Applied N required to achieve 50% of maximum yield was 57 kg ha− 1 and for 50% of maximum plant N uptake was 110 kg ha− 1.