秸秆覆盖量对不同容重黑土坡耕地水土流失的影响

Effects of Straw Mulching on Soil and Water Loss Under Different Soil Bulk Densities on Slope Cropland in Black Soil Region

[目的]研究免耕背景下土壤容重和秸秆覆盖对东北黑土坡耕地水土流失的影响,为东北黑土区保护性耕作技术的改良和推广提供理论依据。[方法]通过模拟传统翻耕和免耕条件下的土壤容重(1.2,1.3 g/cm^(3)),结合不同秸秆覆盖量(0,328,656,984 g/m 2)开展人工降雨试验,对比不同方式下黑土的初始产流时间、产流速率、径流量以及土壤流失量。[结果]①土壤容重的增加显著缩短了初始产流时间并增加了水土流失量。同一秸秆覆盖量条件下,与容重为1.2 g/cm^(3)时相比,1.3 g/cm^(3)容重时的土壤初始产流时间缩短了13.1%~49.9%,径流量增加了0.4%~90.4%,土壤流失量增加了24.6%~302.8%;②与无秸秆覆盖相比,秸秆覆盖下的土壤初始产流时间延长了1.2~2.9倍,径流量减少了3.1%~38.9%,土壤流失量减少了34.0%~97.9%,且秸秆覆盖的保土效果与秸秆覆盖量呈极显著正相关关系(p<0.01,r=0.862);秸秆覆盖量为656 g/m 2时达到最佳的水土保持效果;③土壤容重的增加会加剧黑土水土流失,但秸秆覆盖显著降低了黑土水土流失,综合对比发现土壤容重为1.3 g/cm^(3)时采取秸秆覆盖,平均减少了10.7%的径流量和74.2%的土壤流失量。[结论]为有效防治水土流失,建议东北黑土区免耕时应注意结合秸秆覆盖措施,且秸秆覆盖量保持在656 g/m 2以上为宜。

[Objective]The regulating effects of soil bulk density and straw mulching on soil and water loss on slope cropland in the black soil region of Northeastern China were studied in order to facilitate further improvement and application of conservation tillage practices including no tillage and straw returning to fields.[Methods]Two levels of soil bulk density(1.2 and 1.3 g/cm^(3),representing the soil with conventional tillage and no-tillage practices,respectively)and four levels of straw mulching(0,328,656,and 984 g/m 2)were considered in this study.For these treatments,simulated rainfall experiments were conducted.The starting times and rates of runoff generation as well as the amount of soil and water loss for each treatment were measured.[Results]①Soil and water loss of the treatments with bulk density of 1.3 g/cm^(3) were significantly higher than observed for the treatments with bulk density of 1.2 g/cm^(3).Specifically,the starting time of runoff generation was reduced by 13.1%~49.9%by decreasing soil bulk density,and correspondingly the runoff and soil loss were increased by 0.4%~90.4%and 24.6%~302.8%,respectively,by the decreasing of bulk density;②In comparision to the control(no straw mulching),straw mulching delayed the starting time of runoff generation by 1.2~2.9 times.Straw mulching also reduced runoff amount by 3.1%~38.9%and soil loss amount by 34.0%~97.9%.These decreases in runoff and soil loss were positively correlated(p<0.01,r=0.862)with straw mulching amount.The best performance of straw mulching in conserving soil and water would be obtained using 656 g/m 2 of straw mulch;③The soil and water loss on the black soil slope land was aggravated by increasing soil bulk density,but relieved by increasing straw mulching as a result of the straw returning practice.On average,no-tillage(increasing soil bulk density,1.3 g/cm^(3))and straw mulching practices reduced runoff by 10.7%and soil loss by 74.2%.[Conclusion]In the black soil region of Northeastern China,no-tillage should be practiced in conjunction with straw mulching to prevent soil and water loss on slope cropland,and the optimum amount of straw mulching should be greater than 656 g/m 2.