Synergistic water management enhances rice-rapeseed rotation yields in waterlogged areas: field and modeling evidence
摘要
Mitigating the adverse effects of waterlogging in farmland caused by heavy rainfall and poor drainage is essential for maintaining agricultural productivity and ensuring global food security. This study conducted a two-year field experiment to evaluate different straw blind ditch drainage spacings (2, 3, 4, and 5 m) and subsurface pipe drainage spacings (6, 9, and 12 m), with open ditch drainage as the control (CK). The results indicated that, compared to CK, straw blind ditch drainage reduced the groundwater table and soil water content by 28.0% and 11.3%, respectively. In comparison to subsurface pipe drainage, the reductions were 0.2% and 2.8%, respectively. These findings demonstrate the effectiveness of straw blind ditch drainage in managing water during the rice-rapeseed rotation period. Additionally, reducing drainage spacing significantly enhanced waterlogging alleviation and crop yield regulation. Compared to CK, straw blind ditch and subsurface pipe drainage treatments increased rice yields by 2.01 and 1.93 t·ha–1, respectively, and rapeseed yields by 0.92 and 0.51 t·ha–1, respectively. These increases were relative to the initial yields of 6.40 t·ha–1 for rice and 2.60 t·ha–1 for rapeseed in the control group. Crop yields followed a single-peak parabolic trend as drainage spacing increased. A coupled model for soil water movement and crop growth under varying drainage conditions was developed using the HYDRUS-2D and AquaCrop models. Simulation results showed that when subsurface pipe drainage spacing ranged from 8 to 9.5 m, peak rice and rapeseed yields could reach 8.02–8.13 t·ha–1 and 3.12–3.22 t·ha–1, respectively. For straw blind ditch drainage with spacings from 2.6 to 3.9 m, peak rice and rapeseed yields could reach 7.87–8.41 t·ha–1 and 3.39–3.62 t·ha–1, respectively. This study confirms that optimizing subsurface drainage spacing significantly improves water use efficiency and crop productivity in rice-rapeseed rotations, providing a scientific basis for the sustainable intensification of waterlogged croplands in the middle and lower Yangtze River Basin.