ABSTRACT

To systematically study the soil and water conservation functions of different straw mulching application rates on sloping farmland in karst area of Southwest China, the observation of runoff plots was carried out with natural rainfall. The effects of six mulching gradients (0, 1.111, 2.222, 3.889, 5.556, 6.944 Mg ha⁻¹) on soil and water conservation functions (soil moisture, nutrients, runoff and sediment yields) were showed: with an increasing straw mulching, total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), soil moisture and available nutrients increased, and high straw mulching (SM₄ and SM₅) made them significantly higher than control, but there was no significant difference between SM₄ and SM₅; the contents of soil moisture, TOC, TN, TP and available nutrients of mulching treatments in 2019 except for total potassium (TK) were higher than those in 2018; with an increasing straw mulching, the runoff and sediment yields decreased exponentially, while the straw mulching reached 5.556–6.944 Mg ha⁻¹, it didn’t change significantly. These results suggested that straw mulching about 6 Mg ha⁻¹ should be adopted for sloping farmland in karst area of Southwest China, and appropriate K fertilizer should be added to maintain the balance of K in soil.

摘要

为系统研究西南岩溶区坡耕地不同秸秆覆盖施用量的水土保持功能，利用自然降雨对径流样地进行观测。显示了六种覆盖梯度（0、1.111、2.222、3.889、5.556、6.944 Mg ha ^-1）对水土保持功能（土壤水分、养分、径流和泥沙产量）的影响：随着秸秆覆盖的增加，总有机碳（TOC）、全氮（TN）、全磷（TP）、土壤水分和速效养分增加，秸秆覆盖（SM ₄和SM ₅）使其显着高于对照，但无显着差异SM ₄和 SM ₅; 除总钾（TK）外，2019年覆盖处理土壤水分、TOC、TN、TP和速效养分含量均高于2018年；随着秸秆覆盖的增加，径流和产沙量呈指数下降，而秸秆覆盖达到5.556~6.944 Mg ha ^-1，变化不大。这些结果表明，西南喀斯特地区坡耕地宜采用秸秆覆盖6 Mg ha ^-1左右，并适当添加钾肥以维持土壤中钾的平衡。