A comprehensive experimental study with mathematical modeling to investigate the affects of cropping practices on water balance variables

Winter cover cropping may mitigate the adverse effects of conventional cropping practices (bare soil during winter) by reducing runoff and increasing infiltration of rainfall. However, cover crops also deplete water through evapotranspiration. An experimental study was conducted and a numerical modeling was developed to investigate the effects of cropping practices on water balance variables (e.g., recharge, evapotranspiration, etc.). An automated calibration procedure was adapted in MIKE SHE (physically based hydrologic model) in conjunction with PEST (parameter estimation model) to optimize effective model parameters based on measured soil water content (SWC) data. The simulation performance of the calibrated model over the validation period indicated that the model is able to simulate SWC with a reasonable degree of accuracy. Finally, the model was used to investigate the effects of cropping practice scenarios on water availability. The experimental results indicated that cropping practices do not significantly affect SWC; rather crop rotation and soil spatial variability largely influence water distribution and availability in the subsurface system. The modelling results were consistent with the observed data. Simulation analyses indicated that cover cropping may not be a viable option in semiarid regions; however, the practice may increase infiltration in humid regions. Early cover crop termination and surface mulch in semiarid regions could increase the water availability and protect the soil surface from raindrop impact thus enhancing infiltration. Pre-irrigation before and during cover cropping period may increase water availability and improve cultivation activities.