干旱区生态环境知识资源中心

This paper is aimed at examining the role of soil moisture modeling in agricultural water management in a semi-arid region where rain-fed agriculture is practiced. For this purpose, we developed a daily-time step soil moisture accounting model and simulated components of soil moisture, evaporation, surface runoff, and deep percolation using forty-two years of daily agro-climatic data and cropping cycle data of maize and sorghum. Using a sustainability criterion on crop water requirement and soil moisture availability, we also determined sustainability of rain-fed agriculture of maize and sorghum. These soil moisture simulations revealed further confirmation of the relative sensitivity to drought of these crops, which we found are consistent with the Agromisa recommendations. The developed soil moisture model was finally used for simulation of the daily direct surface runoff, in which we found that under planting of both maize and sorghum, a surface runoff of about 5 min/day could be available for 10% of the simulated days. We explored the opportunities and constraints of this excess water harvesting in order to implement agricultural water management practices in this semi-arid region of Botswana.