Study On The Hillside-land Soil Erosion Of The Loess Plateau And Its Influence On Productivity

Being the birthplace of the Chinese Nation, the Loess Plateau has a vast territory and rich natural resources. However, with the rapid growth of population and overexploitation of resources in recent years, the forest and grass vegetation was seriously damaged and the soil erosion was aggravated, moreover, the land was degrading in a rapid speed, and the ecological and production conditions became worse. This paper paid much attention to the evolvement characteristic of the hillside-land soil erosion of the Plateau and the main problems existing in production and resource utilization. Based on the concept of sustainable development and the systematic and scientific ideation, regional hillside-land soil erosion and its influence on productivity were studied through establishing mathematical model and making qualitative analysis and quantitative analysis jointly. Main achievements included:(1) Many factors, such as the measures of land cultivation, cropping pattern, crop growing structure and etc, had actual influence on the form and intensity of the soil erosion of the Loess Plateau, and on the land degradation and productivity decline as well;(2) Soil erosion induced the land degradation on the Loess Plateau, which were mainly manifested as the following: the soil layer becoming thinner; and the soil texture tending to be coarse granulation, stony soil or restored parent materials; the content of soilorganic matter and nutrients becoming lower and lower; the capacity of rainfall infiltration becoming less; and physicochemica] properties of the soil deteriorated; (3) Synthesis judging models are set up, which contain:a. synthesis judging model of soil quality by minimum factor.b. synthesis judging model of soil quality by illegibility theory.The judging models on the affection of soil corrosion to the quality of brae are also established:a. retrogression judging model of the quality of brae by gradual-change corrosion.b. retrogression judging model of the quality of brae by accumulative-total corrosion.(4) The percentage of hillside-land productivity decline in unit time could show the intensity of land degradation, the lower the soil erosion intensity was, the weaker the land degradation intensity would be, correspondingly, the higher the soil erosion intensity was, the heavier the land degradation intensity would be.;(5)The hillside-land degradation of the Loess Plateau could be reduced to three types, which were, the degradation induced by the thinning of soil layer, the degradation induced by the soil texture tending to be stony soil or restored parent materials, and the degradation induced by the loss of soil nutrients respectively;(6) It would be a system engineering to improve the productivity of hillside land on the Plateau, which would involve the structural optimization and adjustment of hillside-land utilization, effective configuration and management of vegetation, and the organic integration of biological measures, engineering measures and agricultural technologies. Structural optimization and adjustment of hillside-land utilization should be the heart of the matter, and the rebuilding of vegetation and effective utilization of natural rainfall should be the key section.