Crop response functions integrating water, nitrogen, and salinity

Process-based simulation models are used to generate seasonal crop yield and nitrate leaching datasets for several important crops. The simulated data is then used to estimate novel three-input crop response functions that account for the effects of interactions and feedback mechanisms in the whole plant–water–nitrogen–salinity system. Comparisons with available field data show that this appears to be a reliable approach for estimating analytical crop response functions with water, nitrogen, and salinity as input factors. Results also demonstrate the shortcomings of using simpler two-input functions. The estimated functions are continuously differentiable and can be easily incorporated into comprehensive agricultural–economic–environmental optimization models, thus facilitating greater utilization of process-based models by a wider range of disciplines.