模拟降雨下土壤前期含水量对土壤可蚀性的影响

Effect of antecedent soil moisture on soil erodibility using simulation rainfall

土壤前期含水量是导致土壤可蚀性动态变化一个重要因素。利用人工模拟降雨试验,以我国亚热带地区的14种典型土壤为研究对象,在各试验小区上分别设定3种不同的土壤前期含水量水平,研究土壤前期含水量对不同土壤可蚀性的影响。结果表明,14种土壤类型在3种不同土壤前期含水量水平下土壤可蚀性K值都存在动态变化,但不同土壤类型其可蚀性K值随土壤前期含水量变化的变动幅度不同,同一土壤可蚀性K值在土壤前期含水量变化范围内最高和最低值之间最高相差达到16倍;不同土壤类型可蚀性K值随土壤前期含水量变化的变动趋势也不同,其中绝大多数土壤可蚀性K值随前期土壤含水量的升高而增大,根据土壤可蚀性K值的变动趋势可以分为三类,首先,9种土壤的可蚀性K值随前期土壤含水量的升高而增大;其次,4种土壤可蚀性K值随前期土壤含水量升高先升高后降低,变化趋势大致呈倒"U"型;第三,仅有1种土壤的可蚀性K值随土壤前期含水量的升高而减小。

Antecedent soil moisture content is a very important factor leading to soil erodibility dynamic change. 42 artificial simulated rainfall experiments were conducted in 14 soil erodibility plots with different soil types in South China, and the impact of three antecedent soil moisture levels （dry, dampish, wet） on soil erodibifity K value were studied as well. The results showed that soil erodibility K value was affected by antecedent soil moisture content. Also, the change pattern of soil erodibility K value varied with different soil types. For the same soil type, the highest value was 16 times greater than the lowest value within the range of antecedent soil moisture content. For the different soil types, different pattern of soil erodibility K value was found with the change of antecedent soil moisture content. The change trend of soil erodibility K value was sorted into three types： Firstly, the soil erodibifity factor K values for nine soil types would be going up with the increase of the antecedent soil moisture content; Secondly, the change trend of soil erodibility K values for four soil types presented inverse ＂U＂ shape with the change of antecedent soil moisture content; Thirdly, the soil erodibifity factor K values for one kind of soil would be going down with the decrease of the antecedent soil moisture content.