辽西褐土和棕壤溅蚀效应与团聚体分选特征

Splash erosion effect and aggregate sorting characteristics of cinnamon soil and brown soil in the western Liaoning province

为了探究辽西低山丘陵区坡耕地土壤溅蚀机理,选取褐土和棕壤为研究对象,采用人工模拟降雨试验研究一定降雨能量下土壤溅蚀量与团聚体分选特征。结果表明:1)褐土和棕壤不同方向溅蚀量以及净溅蚀量与溅蚀距离呈对数递减关系。不同水平距离范围内,褐土下坡溅蚀总量是上坡溅蚀总量的4.25倍,棕壤下坡溅蚀总量是上坡溅蚀总量的4.85倍。褐土和棕壤水平距离为0~5 cm时溅蚀量和其他水平距离溅蚀量呈极显著差异。2)溅蚀对褐土和棕壤大团聚体富集作用与损耗作用的临界团聚体粒级为1 mm,当团聚体粒级>1 mm时,棕壤的富集率明显大于褐土;当团聚体的粒级<1 mm时,褐土的团聚体富集率明显大于棕壤。3)褐土和棕壤在各水平距离范围均未出现>5 mm的水稳性团聚体,>0.50~1.00 mm水稳性团聚体和>0.25~0.50 mm水稳性团聚体均出现在试验设计的水平距离范围内,褐土相比棕壤>0.25~1.00 mm粒级的团聚体,随水平距离的变化不管是增大幅度还是减小幅度,均表现为褐土大于棕壤。褐土和棕壤不同水平距离范围内各个粒级水稳性团聚体平均质量直径均<1 mm,褐土随着水平距离的增大团聚体平均质量直径表现为先增大后减小,棕壤随着水平距离的增大团聚体平均质量直径表现为逐渐减小。

[Background]As an important cultivated land resource,sloping land accounts for 82.65%of the total cultivated land area of western Liaoning province.In addition,due to poor vegetation coverage,the area of soil erosion accounts for 41.6%of the total area of this area,which is the most serious area of soil erosion in Liaoning province.Cinnamon soil and brown soil are the main types of soil in this area.Because of their loose structure and low content of organic matter,rainfall very easily causes soil erosion.[Methods]Typical sloping farmland of cinnamon soil and brown soil with a slope of 10°was selected to collect the topsoil(0-20 cm),and 5 sample points were selected according to the“S”sampling method.They were directly dug and bagged in the field,dried and screened through a 10-mm screen in the laboratory.Norton artificial simulated rainfall apparatus was used to conduct rainfall simulation experiments.[Results]1)In the range of different horizontal distance,the total amount of spillage in the lower slope of brown soil is 4.25 times of that in the upper slope,and the total amount of spillage in the lower slope of brown soil is 4.85 times of that in the upper slope.When the horizontal distance between cinnamon soil and brown soil is 0-5 cm,the spillage amount is significantly different from that of other horizontal distance.2)When the aggregate size was>1 mm,the enrichment rate of cinnamon soil was significantly higher than that of brown soil.When the aggregate size was<1.00 mm,the enrichment rate of brown soil was significantly higher than that of brown soil.3)There were no>5.00 mm water-stable aggregates in the cinnamon soil and brown soil in the range of horizontal distance,>0.50-1.00 mm water-stable aggregates and>0.25-0.50 mm water-stable aggregates in the range of horizontal distance designed by the test.The average weight diameter of water-stable aggregates in different horizontal distance ranges of cinnamon soil and brown soil was less than 1 mm.With the increase of horizontal distance,the average weight diameter of cinnamon soil increased first and then decreased,while the average weight diameter of brown soil decreased gradually with the increase of horizontal distance.[Conclusions]The amount of spillage in different directions and the net amount of spillage and the spillage distance are logarithmically decreasing.The critical aggregate size for enrichment and loss of cinnamon soil and brown soil by splash erosion is 1.00 mm.Compared with brown soil,the aggregate size of>0.25-1.00 mm increases or decreases with the change of horizontal distance,which is cinnamon soil>brown soil.