Interactive effects of tillage and straw mulching on surface runoff, nutrient loss, and maize yield on sloping farmland with purple soil in China

Investigating the impacts of different management practices on soil erosion and nutrient loss in purple soil sloping farmlands can contribute to the optimization of management strategies. The best tillage system for sustainable agriculture within this region remains unknown. Therefore, a seven-year field experiment was carried out at 15 randomly selected experimental sites, aiming to determine the effects of no tillage (TR1), ridge tillage (TR2), strip tillage (TR3), ridge tillage with straw mulching (TR4), and strip tillage with straw mulching (TR5) methods on runoff depth, nutrient loss, soil chemical properties, and maize yield. The results indicated that, compared with those under no-till, runoff depth and nutrient losses (nitrogen: N and phosphorus: P) under all conservation tillage practices were reduced over 60–90 %. The runoff depth was the lowest in TR4, while the nutrient losses were the lowest in TR4 in dry years and normal years, and in TR5 in wet years. The dissolved form made up the majority of N (71–90 %) and P (58–79 %) losses in runoff. Straw mulching was positively correlated with soil chemical properties, and the annual soil organic carbon (SOC) increased significantly under TR4 (up to 31 %) and TR5 (up to 17 %) compared with other treatments. Compared with those of the TR1 method, maize yield and nutrient uptake responses were positive for the TR4 method in dry years and normal years, and for the TR5 method in wet years. Overall, these results will offer more precise management suggestions for the optimization of the interaction between straw return and soil tillage, reducing nutrient loss by water erosion, as well as advancing the conservation and sustainable utilization on the sloping land of purple soil in Southwest China.