Numerical simulation of water- and heat-flow regimes of mulched soil in rain-fed soybean field in central Japan

Numerical simulations for predicting soil-water and heat-flow regimes beneath mulched soils are important to increase the opportunity for efficient use of mulching in agriculture. This study simulated water and heat flows by HYDRUS-1D model under rice-straw mulching and bare soil treatments for rain-fed soybean (Glycine max) cultivation at Gifu Prefecture in central Japan. Soil hydraulic and thermal parameters with the straw mulching were optimized by adding a hypothetical 3-cm straw layer. The optimized parameters were validated with field-measured soil-moisture and temperature regimes of two consecutive soybean-growing seasons of 2015 and 2016. HYDRUS-1D model performed fairly well in simulating heat and water movements at 5, 15 and 25 cm soil depths under the two treatments. The model simulated soil moisture and…