不同坡度下掺沙对黑土坡面径流侵蚀特征的影响

Effects of Soil Mixed with Sand on Slope Erosion at the Mollisol Hill Slope

黑土区野外考察发现,当地农民通过土壤掺沙的方法改良土壤质地,以提高作物产量。鉴于此,基于人工模拟降雨试验,探究东北典型坡度(3°,5°和7°)条件下掺沙比例(0,10%,20%和30%)对黑土坡面径流侵蚀特征的影响,以期为东北农业生产和土壤侵蚀防治提供科学依据。结果表明:掺沙比例对坡面径流特征的影响较坡度更加明显;随着坡度的增加,掺沙比例对径流特征的影响增大。随着掺沙比例的增加,平均径流流速从5.2~5.3 cm/s减小到2.7~3.4 cm/s,产流率和径流量逐渐减小,掺沙30%时达到最小值。产沙率随掺沙比例和坡度的增大呈先增加再减小的变化。侵蚀量随掺沙比例增大变化显著,呈先增加后减小的变化,在掺沙10%和20%时较大。可见,土壤掺沙(<20%)在减小坡面径流量的同时,亦能增加坡面土壤侵蚀量。从水土保持角度分析,掺沙处理不利于防治黑土坡面土壤流失,但是综合考虑其生态经济效益,适度掺沙能够作为一种黑土区坡耕地农业技术措施。

In order to increase crop yield,farmers usually improved soil texture by mixing soil with sand in the Chinese mollisol region.This study was conducted to analyze impacts of different proportions of soil mixed with sand(0,10%,20%and 30%)on slope erosion under three slope gradients(3°,5°and 7°)based on simulated rainfall experiments.The results would provide scientific foundation for agricultural production and soil erosion control in this region.The results showed that the impacts of different proportions of soil and sand mixture on runoff were greater than those of slope gradients,which increased with the increase in slope gradient.As the proportion of sand mixed in the soil increased,the mean runoff velocities varied from 5.2~5.3 cm/s to 2.7~3.4 cm/s and runoff rates and total runoff also decreased with the minimum values occurred in the 30%treatments.Sediment rates first increased and then decreased with the increasing proportion of sand mixed in the soil and slope gradient.Similar trend was found in sediment yields and the 10%and 20%treatments had the greater values than others.It could be include that soil mixed with sand less than 20%could decrease the runoff but increase soil erosion.Therefore,the effects of soil mixed with sand cannot provide a comprise solution for preventing soil loss in Chinese mollisol region.However,a moderate proportion of sand mixed in the soil can be used as an altenative agriculture technical measure by considering its ecological and economic benefits.