不同土地利用方式下农地土壤侵蚀与养分流失

Soil Erosion and Nutrient Loss of Various Land Use Patterns

苏南丘陵区存在多种利用当地土地资源方式,诸多利用方式也改变了土壤的性能,一般是人类干预下的耕地的土壤侵蚀及养分流失高于处在自然半自然状态下的非耕地。为了定量了解由土壤侵蚀引起的养分流失,首先应掌握土壤侵蚀的强度,137Cs示踪法可以对此提供帮助。使用此法需解决2个问题:确定研究区域的137Cs背景值与建立估算土壤侵蚀的模型,我们在这方面做了合理的尝试。以此为基础,估算了各种利用方式下土壤养分流失量;为了与黄土和红壤区土壤侵蚀的危害相比较,提出了等值侵蚀模数的概念,以便揭示苏南地区土壤侵蚀的潜在危害性。通过研究初步确认耕地尤其是水田可能是太湖水体营养元素的主要农业来源。

The favorable natural condition is advantageous to various land use patterns in low mountains and hills of south Jiangsu province. And various ways of land uses have changed the properties of the soil. In general, the soil erosion and the nutrient loss of the cultivated soil that are disturbed by human are larger than that of the uncultivated soil in natural or halfnatural condition. In order to know the quantity of nutrient loss caused by soil erosion, the soil erosion intensity should be decided. The tracer method by cesium-137 can be used to resolve two problems. One is to determine the background content of137Cs. The other is to establish the model of soil erosion. After estimating the soil erosion rate of various ways of land uses, the quantity of soil nutrient loss is calculated. For the sake of indicating the potential risk of soil erosion, and comparing the danger of the loess with red soil area, the concept of the equal value soil erosion is put forward. It is preliminary found that cultivated soil, especially paddy, may be a primary agricultural source of nutrient elements of Taihu lake. 