中文摘要：

土壤抗侵蚀能力特征是土壤侵蚀预测预报的重要依据之一,为了分析黄土区不同生长期大豆坡耕地土壤抗侵蚀能力特征,采用原状土冲刷槽和静水崩解法,分别在大豆不同生长期测定坡耕地不同土层土壤抗冲性和抗蚀性,并对大豆根系特征与土壤抗侵蚀能力的关系进行分析。结果表明：随着大豆生育期的推进呈现出先增强后减弱的趋势,始粒期土壤抗侵蚀能力最强,苗期最弱;在大豆苗期与分枝期,土壤抗侵蚀能力随土层深度的增加而减弱;大豆开花期以后10~20 cm土层土壤抗侵蚀能力最强,其次为0~5 cm土层;土壤根重密度、根系表面积、根系体积及根系长度对土壤抗侵蚀能力影响均达到极显著水平（p〈0.01）,且根径在0~0.5 mm之间根系的增多会更加有效地提高土壤的抗侵蚀能力。这表明在大豆生长初期加强对坡面的有效防护,避免地表长期裸露,培育根系发达的大豆品种将有助于对坡耕地土壤侵蚀的防控。

英文摘要：

【Objective】Soil erosion resistance is one of the main factors affecting development of soil erosion. As the Loess Plateau is one of the most severe soil erosion areas in China,it is especially important to characterize the soil erosion resistance of the region to management and control of soil erosion on the Loess Plateau. Soybean,high in drought resistance,is one of the major crops commonly grown on the Loess Plateau,and the one that grows in the season when heavy rain showers occur frequently,and consequently soil erosion tends to take place in the region. Therefore,a field experiment was conducted to determine characteristics of the erosion resistance of the soil and their relationships with soybean root system relative to growth stage of soybean.【Method】Soil anti-scourability and anti-erodibility are two important parameters to evaluate soil resistance. This study determined the soil anti-erosion ability characteristics based on soil antiscourability and anti-erodibility. Based on the determination of the two indices,soil anti-scourability and antierodibility,soil erosion resistance was characterized. As soil anti-scourability index and soil disintegration rate can well reflect characteristics of soil anti-scourability and anti-erodibility,these two parameters were selected to evaluate soil anti-scourability and anti-erodibility. Soil anti-scourability index refers to the time it takes for rain water to wash off a gram of soil（min g-1）,and soil disintegration rate to the amount of soil disintegrated within a set unit of time（g min-1）. The effect of soybean roots enhancing soil erosion resistance is evaluated by measuring how much soil anti-scourability and soil anti-erodibility is enhanced by the root system of soybean at different growth stages of the crop. 【Result】 Results show that soil antiscourability and anti-erodibility varied with the crop growing,showing a similar trend.Soil anti-scourability index increased significantly from the seedling stage to the pod bearing stage of the cro