Optimizing agricultural water use through simulation of soil water content and water uptake under soil moisture and irrigation water salinity stresses: Case study of corn roots using SWAP model

In order to evaluate soil water content and water uptake by corn plant roots (Single cross ۲۶۰) under different soil moisture and water salinity stresses using the agro-hydrological Soil–Water–Atmosphere–Plant (SWAP) model, an experiment was conducted in ۲۰۱۵ at the green house of the Agriculture Research Center of Shahrood, Iran. The statistical model employed was a split plot based on a randomized complete block design with three replications. The main plots consisted of three levels of irrigation; ۵۰ (I۱) (full irrigation as the control), ۷۵ (I۲) and ۱۰۰% (I۳) of Total Available Water (TAW) depletion while the sub-plots consisted of three levels of salinity of irrigation water; ۲ (S۱), ۴ (S۲) and ۶ (S۳) ds.m-۱. The results showed a good correspondence between the simulated soil moisture, water uptake and measured values. The normalized root mean square error (nRMSE) and the root mean square error (RMSE) values of the predicted soil moisture were ۴.۵۸ and ۲۴.۹۶ and for the water uptake by the roots were ۲۳.۳۷ and ۳۵.۴۸, respectively. The R۲ of coefficient of simulation for water uptake by roots in different treatments were ۰.۳۸ to ۰.۸. The dataset of the predicted and measured values were close to the ۱:۱ scale line for both soil moisture and water uptake. This study indicated that the SWAP model can be used as a powerful tool to simulate field water cycle and evaluate irrigation practices. Accordingly, taking into account the existing conditions of the region such as weather and soil type and preparing scenarios based on possible management options, management strategies can be optimized according to the results achieved for the SWAP model simulation.

Keywords:

Total available water depletion , water uptake , Irrigation management , Soil hydraulic parameters , SWAP