| Soil erosion in China is serious and causes ecological problems such as river jams, floods, nutrient loss, water pollution, soil degradation, and decrease in land productivity. It has negatively impacted on sustainable agricultural development, and this made many people pay attention. At present there are more reports on soil erosion by experts from home and abroad, but most of these reports were about simulation and research based on a single factor. There are little reports on soil erosion on entire watershed, adopted comprehensive research measures according to the principle of ecological system, especially on soil erosion from the intensive farming system on slope lands, watersheds exploited for agroforestry industry, as well as appraisal reports on soil fertility index. Soil erosion and nutrient losses in Jiangjiatang watershed in Lanxi city in Zhejiang province during exploitation was studied from 1993-2000 using adoptive research methods such as runoff plot, catchment area, and rare earth element tracer (Eu) , and the soil fertility index appraisal. The major conclusions are as follow:1. The principle of water and soil losses together with nutrients and the forms in which they were lost were studied under different fanning systems in runoff plot. The results show that(1) The system of contour dams, contours and fallow had positive impact on water and soil losses than grass stripes and contour ditch. At the same time it was showed that contour dams, contours, fallow significantly reduced soil erosion and water loss, grass stripe and contour ditch had recorded reduction in water and soil losses although to a much less extent than above 3 farming systems. Most of sediment was bed load in all the systems except in contour dams and contour fanning. The runoff and sediment deposition during the period May to August accounted for more than 80% of annual runoff and sediment deposit, this was due to the fact that during this period the area receives higher precipitation and rainfall. Additionally our findings were mat precipitation, rainfall index, plant coverage had impacted differently on runoff and deposit of sediment in different fanning systems.(2) The losses of organic carbon, nitrogen, phosphorus and potassium were different in different farming systems. This losses of these elements according to respective farming systems was the following order: tradition>grass stripe>contour ditch>fallow>contour dam. Compared with traditional fanning practices, others farmingsystems reduced losses of organic carbon, nitrogen, phosphorus and potassium and losses in contour dam, contour and fallow were much less than grass stripe and contour ditch.(3) The farming systems which had a less degree of soil erosion and sedimentation, organic carbon was lost mainly through runoff but in farming systems in which soil erosion was serious such as in grass stripe, contour ditch, traditional farming system, the loss was through bed load. Nitrogen loss through runoff was 81.9%-93.4% of the total. This loss through runoff comprised 78%-87.6% dissolved NHVN and NO"3-N although the former was slightly higher than latter as it made up 55.14% of the lost nitrogen. The quantities of organic carbon and nitrogen in the bed load were high than in the runoff plots and this had a nutrient enrichment phenomenon. The losses of organic carbon, nitrogen were concentrated in May to August accounting for more than 83%.(4) The percentage phosphorus loss by bed load was equivalent to mat lost as a result of runoff in traditional fanning practices, whereas in the rest of farming system the loss by runoff phosphorus was 67.59%-88.11%. Potassium lost by runoff in systems, which had less sedimentation such as contour, and contour dams, was 71.34% and 65.79% respectively of total. Potassium lost by runoff was equal to that lost by bed load in fallow farming system, but in the systems with more sediment such as traditional farming system, grass stripe, and contour ditch potassium loss was mainly through bed load whic...
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