谷子冠层下的土壤溅蚀速率特征

Characteristics of splash detachment rate under millet canopy

为研究种植谷子(Setaria italica Beauv)条件下农地土壤溅蚀速率的变化特征,评价谷子冠层对土壤溅蚀的影响,采取室内模拟降雨手段,利用溅蚀杯法分别测定了叶面积指数为0.86、1.54、2.18和3.11四个生长阶段的谷子冠层下以及裸地上的溅蚀速率。谷子冠下溅蚀速率测定的设计雨强为40 mm/h和80 mm/h,裸地试验的设计雨强为20、406、0、80、1001、20 mm/h及140 mm/h。试验结果表明:与裸地相比,在各生长阶段,谷子冠下的平均溅蚀速率在40 mm/h雨强下平均降低24%,在80 mm/h雨强下降低约52%,特定条件下冠下溅蚀速率会高于相同雨强下裸地的溅蚀速率;冠下平均溅蚀速率的变化与冠层发育之间的关系不明显;谷子冠下各地点的溅蚀速率与该地点对应的冠下雨强之间的关系不显著,而裸地上溅蚀速率与雨强之间呈幂函数相关关系。

The objective of this study was to investigate the characteristics of splash detachment rate under millet （ Setaria italica Beauv） canopy compared to bare ground. The experiment was conducted using an indoor rainfall simulator. The detachment rate under millet canopy with different LAI from about 0.86 to 3.11 and on bare ground was measured using splash cups. The designed rainfall intensities of 40 and 80 mm/h were applied when detachment rate was measured under canopy, and intensities of 20, 40, 60, 80, 100, 120 and 140 mm/h were applied on bare ground. Compared to bare ground, the average detachment rate under millet canopy through growing season reduced by about 24 % with designed rainfall intensity of 40 ram/h, and reduced by about 52 % with intensity of 80 mm/h. The detachment rate under millet canopy might be higher than that on bare ground under certain conditions. There was no obvious relationship between changes of average detachment rate under millet canopy and canopy development. Under millet canopy, no significant relationship was found between the detachment rate at different positions and corresponding rainfall intensity at the same place, but on Lare ground, there was a significant exponential relationship between detachment rate and rainfall intensity.