密云石匣小流域土地利用对土壤粗化的影响

在北京密云石匣小流域坡面径流试验小区的坡耕地、休闲地和荒草地的坡上部、坡中部和坡下部,分别对表层和剖面进行了采样,用筛分的方法分析土样中大于2mm石砾所占百分数来确定不同土地利用下的土壤粗化程度。试验结果表明:休闲地、坡耕地和荒草地小区的土壤粗化程度为休闲地>坡耕地>荒草地。假设荒草地石砾所占百分数为正常值,用某种土地利用方式下石砾所占百分数与荒草地石砾所占百分数的比值来表示该土地利用下的土壤粗化程度指数,则0-1cm土层休闲地和坡耕地的粗化程度指数分别为2.96和2.07。土地利用方式不同,剖面层间的粗化特性也存在差异。荒草地剖面层不存在土壤粗化;休闲地和坡耕地剖面层则存在土壤粗化。本研究可为土壤退化等级评价和土地利用规划提供基础资料

The impact of land use on soil texture in Shixia watershed of Miyun County, Beijing

Varying soil loss resulting from different land use leads to problems of soil coarsening to different degrees in Beijing hilly area. In this paper, the data of conventional tillage plot, the fallow plot and the wasteland plot at Miyun county, Beijing were used. The topsoil samples and profile samples were taken from the upper, middle and down slopes of the plots. The soil samples were sieved. Then the rock fragment samples, whose diameter is over 2 mmeach, were weighted by means of sieving. The percentage of rock fragments in the samples was calculated. The results show that thepercentageof rock fragments in fallow plot is the highest and the percentageof rock fragments in wasteland is the smallest. Provided the percentage of rock fragments in the samples of wasteland was known at a normal value, and the soil textureindex was expressed with the ratio of the percentageofrock fragments for other land use to the one in wasteland, then the indexes of fallow land, conventional tillage plot and wasteland are 2.96, 2.07 and 1, respectively. The characteristic of soil coarsening in section varies with different land use purposes.The section at wasteland is free from soil coarsening, while the sections at fallow plot and conventional tillage plot experience apparent soil coarsening. The results can be applied for land use planing and soil degradation evaluation.