Analysis of Impact of Soil Erosion on the Slope Farmland on the Loess Plateau

摘要

The serious soil erosion brought soil fertility degradation, soil environment quality deterioration, and lead to low yield grain production in loess plateau. Soil nutrient loss, soil physical property degeneration and soil enzyme activity reduction to cause low yield were discussed by combining located observation, typical field investigation and laboratory analysis. When the degree of slope increased from 4o to 16owithout fertilizer application, the loss of organic matter increased from 107.9kg ha-1 to 210.0kg ha-1, total nitrogen from 14.8kg ha-1 to 26.1 kg ha-1 and total phosphorus from 4.41 kg ha-1 to 13.3 kg ha-1. These results lead to "barrenness", "coarseness" and "calcification" of the loess soil. Due to soil erosion, the content of particle size less than O.Olmm in slope farmland accounts for only 21.5%, which is equal to a half of that without erosion. At same time soil fertility and amylase activity in slope land decrease with the slope degree increase, and the relationships between them can be described by the index function. According to the data, a simple assessment of the impact of erosion on soil quality was made and divided the quality levels were divided into five grades, including good, fairly good, poor, extremely poor and deteriorated. This scheme provides a scientific basis for remaking and using soil resource.