Analysis On The Processes Of Water And Soil Losses And Measure Layout Of Soil And Water Conservation On Red Soil Slopeland

Red soil on sloping fields developed from bedrock regolith. It had 53 percentages of the red soil area and 12 percentages of the whole country area. Water and soil loss on sloping fields with red soil was severity because of the thin soil layer. It leads to the decline of soil fertility, thinning of soil layer as well as the landification with different degrees. All above were badly harmful to agriculture. So, the most important things for applying sloping fields with red soil are to control water and soil loss, improve soil quality and enhance soil fertility. They were also significant to keep ecology in balance and develop the agriculture on areas with red soil.The paper was focus on the water and soil loss in sloping fields with red soil in Zhejiang province on the basis of former research productions. Experiments of water and soil loss aroused by simulated rainfalls were carried for the research on the characteristics of the water and soil loss in sloping fields with red soil under different water and soil conservation measures on the basis of analyzing data of experimental units in Lanxi Water and Soil Conservation Experimental Station. The optimized patterns were designed among different water and soil conservation measures on sloping fields with red soil. The main research conclusions were listed as follows:1. By analyzing the states of the water and soil loss in Zhejiang province synthetically, the spatial-temporal characteristics were recapitulated as follows: the water and soil loss on sloping fields with red soil was with large areas, high intensities, various types, diverted space distributions, concentrated time distributions and frequent trend changes, as well as distinct water and soil loss caused by human.2. On the basis of analyzing data of thirteen experimental plots in Lanxi Water and Soil Conservation Experimental Station, some conclusions can be summarized: in farming experimental plots, relations among rainfall and runoff and soil erosion were very intricate, but relations between the runoff and soil erosion were obvious. In woodland experimental plots, relations between rainfall and runoff were very distinct, while the corresponding rules of runoff and soil erosion were different. The relation between rainfall and runoff and the relation between rainfall and soil erosion were corresponding well in tea garden and barren sloping field units.3. Sand loss increased with the rainfall intensity increasing under the same slope. The changing rule of percentages of sand in runoff was intricate in the process of rainfall. The soil erosion in the initial stages of rainfall was large, and then kept steady, and the rule was more obvious under higher rainfall intensity. There was more soil loss on the steeper slope under the same rainfall intensity. But the changing rules of percentages of silt content in runoff were intricate, such as more sediment yield under smaller slope4. Compared the different planting patterns on farmland, the effects of cultivation with longitudinal slope on reducing runoff and soil loss were lowest and fluctuated greatly while the effects of cultivations with cross-slope furrow, cultivations along contour line and terrace were best. The cultivations along contour line and terrace reduced soil loss and runoff fastest. Engineering measures on the surface of sloping fields were efficacious on water and soil loss. Terrace was the most effective engineering measures to control water and soil loss. Cross-slope furrows and horizontal stairs were also effective measures in Zhejiang province. There were the more efficacious functions in mixed woodlands without hoe and the worse efficacious functions in man-made production forests.5. In view of the above results, the better complex patterns of farming land and woodland without hoe were designed to control water and soil loss. For examples, they were the combined pattern of orchard and farming land, alternation strip pattern of orchard and farming or protective pattern of orchard and woodland, protective strip pattern of farming and woodland, combination pattern of woodland and tea. The ecosystem Engineering of controlling water and soil loss measures were designed. Such as, they were primarily with increased cover ratio to control water and soil loss, ecological measures with protection and planting to control water and soil loss, ecological resumption pattern with exploitation by human.