NUMERICAL SIMULATION ON SOIL MOISTURE AND HEAT TRANSFER IN COTTON FIELD UNDER MULCHED DRIP IRRIGATION CONDITION

摘要

Soil heat and moisture condition is of critical importance for crop growth and yield. Mulched drip irrigation can improve the water use efficiency and root zone soil heat content. This is less studied through soil moisture and heat transfer simulation. In this study, field experiments were conducted in irrigation experimental station in Xinjiang Province of China during 2008 and 2009 (for cotton crop under mulched drip irrigation), and the software VS2DHI developed by the U.S. Geological Survey (USGS) was used to explore the movement and distribution of soil moisture and heat on a daily basis. The software result was calibrated using the monitored data. The study confirms the sinusoidal pattern of soil temperature during the crop growth period, which is primarily driven by solar radiative force, while the fluctuation of soil temperature is flattened at the deeper soil. The calibration and validation results show that both soil moisture and temperature simulated by VS2DHI agree well with the field data. The influence of mulching on soil moisture is analyzed by the model which shows that the film plays an important role of conserving soil moisture, especially for the surface soil of 40cm depth. More work should be done to improve VS2DHI by coupling ground surface energy processes to evaluate the influence of mulching on soil temperature.