黑土区坡耕地不同秸秆还田方式的水土保持效果分析

为了揭示黑土区坡耕地不同秸秆还田方式的水土保持效果，基于野外原位坡耕地人工模拟降雨试验，以传统顺坡垄作处理为对照，分析50，100 mm/h降雨强度下3种具有代表性的秸秆还田方式（秸秆深还、秸秆碎混和免耕+残茬覆盖）对坡耕地产流产沙过程、径流量、侵蚀量及其减流减沙效益的影响。结果表明：（1）不同秸秆还田方式的产流率皆随降雨量的增加而增大，产流率和产沙率大小均表现为顺坡垄作 > 秸秆深还 > 秸秆碎混 > 免耕+残茬覆盖。（2）与顺坡垄作相比，50，100 mm/h降雨强度下，秸秆还田处理分别延缓产流时间14.0，4.8 min，产流时间的滞后可以体现秸秆还田措施的水土保持效果。（3）秸秆深还、秸秆碎混、免耕+残茬覆盖处理的平均减流效益分别为36.8%，53.9%，65.8%，平均减沙效益分别为84.9%，90.3%，96.8%。可见，免耕+残茬覆盖方式的水土保持效果最好，其次为秸秆碎混和秸秆深还。

Analysis of Soil and Water Conservation Effects of Different Straw Returning Patterns in Sloping Farmland in the Chinese Black Soil Region

The objective of this study was to reveal the soil and water conservation effects of different straw returning patterns at croplands in the black soil region of China. Based on simulated rainfall experiments at field croplands in situ, effects of three representative straw returning patterns (deep application of straw, smashed straw turnover, and no-tillage with straw mulching) on the processes of runoff rates and soil loss rates, total runoff and soil erosion amount, runoff and sediment reduction benefits at 50 and 100 mm/h rainfall intensities were analyzed. The traditional up- and down slope tillage was used as the control treatment. The results showed that: (1) The runoff rates for treatments of different straw returning patterns increased as the rainfall amount increased. Both the runoff rates and soil loss rates decreased in the order of up- and down slope tillage (CK) > deep application of straw > smashed straw turnover > no-tillage with straw mulching. (2) The straw returning treatments delayed the runoff yield time for 14.0 min at 50 mm/h and 4.8 min at 100 mm/h compared with the traditional up-and down slope tillage treatment, which could reflect the soil and water conservation effects of these straw returning measures. (3) The mean runoff reduction benefits for deep application of straw, smashed straw turnover, and no-tillage with straw mulching treatments were 36.8%, 53.9%, and 65.8%, and their mean sediment reduction benefits were 84.9%, 90.3%, and 96.8%, respectively. Therefore, the pattern of no-tillage with straw mulching had the best soil and water conservation effect in this study, which was followed in descending order by the patterns of smashed straw turnover and deep application of straw.