Simulation of Yield Decline as a Result of Water Stress Using BUDGET Model

Abstract

In this paper, to account for the effect of water stresses in the various growth stages under deficit<br />irrigation, the multiplicative, seasonal and minimal approaches are integrated in the BUDGET<br />model. To evaluate the model, the simulated yields for winter wheat (was grown in Sharif Abad<br />district) under various levels of water stress were compared with observed yields. The result<br />showed, simulated crop yields agreed well with observed yields for this location using<br />multiplicative approach (in comparison with minimal and seasonal approaches). The determination<br />coefficient (R2) between observed and simulated yields ranged from 0.81 to 0.92 with very high<br />modeling efficiencies. The root of mean square error (RMSE) values is relatively small and ranged<br />between 6 to 14. A sensitivity analysis showed that the model is robust and that good estimates can<br />be obtained by using indicative values for the required crop and soil parameters