| Currently, soil erosion is becoming the global public hazards and is seriously threatening the survival and development of the human beings. So it is one of the hot issues attracting the popular concerning of the people in the world. In the construction of the ecological environment, to select appropriate agricultural cropping pattern is the need for the agriculture and the important measure for the conservation of soil and water. To develop the suitable cropping patterns to local conditions not only can satisfy the need of survival and diversification of the local peasants, but also can offer better ecological benefits and prompt the sustainable development of the regional agriculture and social economy to move on.According to the investigation, purple soil cropland covered 78.7 percent of the area of total cropland in the Three-Gorge Reservoir Area and the most of the purple soil cropland is slopeland. Based on the former extensive researches, this research observe and evaluate the ecological environmental effects of agricultural cropping patterns in the purple soil area of Chongqing hills in order to improve the quality of the agricultural ecological environment in the focal areas of the country. The plots included Chinese yam and red pepper planting plot, corn and sweet potato planting plot, Artemisia apiacea and purple-flower alfalfa planting plot, purple perilla and Forsythia suspense planting plot. Which were called the number 1,2,3,4 plot respectively. The observed items included soil moisture, soil nutriments and soil erosion etc. The soil nutriments items research included the accumulation and movement of the N, P, K element. The aim of the research was to probe into the course in which the different plants and different cropping patterns in the purple soil area can prevent the loss of soil and water and improve the soil fertility and the ecological environment, further to offer reference for improving the cropping structure and agricultural ecological environment.The result of the research states as follow:(1) During the observing period, the cropping plots covered the surface of earth with the highest covering ratios of 55.2%, 72.0%, 95.9%, 88.3% respectively. The run-off were 296.8mm > 296.1 mm > 274.4mm N 261.8mm respectively. The loss of soil depended on the run-off partly.(2) After a rainfall, the soil moisture in the plot III was the highest, it was 21.33%, and that of in the plot II was the lowest; Meanwhile the conservation ability ofthe soil in the plot III was the highest, that of in the plot II was the lowest.(3) Total nitrogen contents of soil in the cropping plots had little difference at the beginning, then total nitrogen contents of soils all descended except that of forage grass plot. The available nutriments contents of soils in all the cropping plots descended too. The nutriments saturations of run-off were far lower than that of sediment. Total nitrogen and available nitrogen contents of the run-off from the plot II were the highest among the four plots. The available phosphorus contents of the run-off from the plot III and plot IV were higher than that of other two plots' run-off. The nutriments of sediments from the four plots were higher than the nutriments of soil in the plots. The plot II and plot IV had the higher enrichness degree of total nitrogen than the other two plots; The available nitrogen enrichness of sediments from plot IV was the highest, that of from plot Illwas the lowest; The available phosphorus enrichness of sediments from plot IV was the highest, that of from plot Illwas the lowest; The available potassium enrichness of sediments from plot IVwas the highest, that of from plot II was the lowest.(4) The loss of nutriments was made mainly by the loss of soil but loss of water. The sum of the lost total nitrogen in the different plots was in the order plot II >plot III > plot IV > plot I ; The sum of the lost available nitrogen in the different plots was in the order plot III>plot II >plot I >plot IV; The sum...
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