Slope Drainage Engineering Effects On Soil Physical And Chemical Properties And Soil Loss

There were purple soil erosion in severe cases and outstanding contradiction between human and land in the three gorges reservoir at present, soil and water conservation measures are mainly terrace, contour plant hedge, drainage engineering, slope soil conservation tillage, returning farmland to forest and grass, etc... These measures have significant water and sediment reduction benefit. Slope drainage system can reduce the water loss and soil erosion, regulates seasonal agricultural water demand, promote the agricultural increase production has gained recognition and verification, but there is little research about slope drainage engineering affected soil erosion and the effects of soil properties in different land use types.This study area was divided into two groups, group S for slopes with slope drainage engineering-called drainage group, group T for slope without drainage project-called the control group. Each group according to the different methods of land use is divided into four kinds, namely, forest land, grass, ladder flat and slope cropland. We analyzed soil fertility, soil bulk density, moisture content and pore, mechanical components, such as regular soil physical and chemical properties of various land use types in0-20cm soil layer and20-40cm soil layer, and using the137Cs tracer method determined soil erosion of various land use types during the year, and using circular knives and double ring infiltration apparatus test soil permeability. We obtained soil physical and chemical characteristics and soil erosion Different land use types in the slope under the influence of the drainage engineering, provide certain reference basis for the further control of soil and water loss.The results are as follows:(1) slope drainage engineering to add fertilizer had a positive effect.0～20cm soil layer, the influence on forest land and grass organic matter change by slope drainage engineering was not big, but the influence on the ladder flat and slope cropland organic matter content increased was significant.20～40cm soil layer, the influence on slope cropland organic matter change by slope drainage engineering was not significant, but the influence on forest land, grass and ladder flat land organic matter was obvious.0～20cm soil layer, the influence on forest land, grass, ladder flat land and slope cropland total nitrogen content increased by slope drainage engineering was marked;20～40cm soil layer, the influence on ladder flat land total nitrogen by slope drainage engineering was obvious, but change to total nitrogen in forest land, grass and slope cropland by slope drainage engineering was not significant.0～20cm soil layer, the change of forest land, grass, slope cropland alkali solution nitrogen effect by slope drainage engineering was significant, but the ladder flat alkali-hydrolysable nitrogen content change had little impact;20～40cm soil layer, the ladder flat land and slope cropland alkali-hydrolysable nitrogen effected by slope drainage engineering was not significant, but forest and grass alkali solution nitrogen increasing effect was obvious.0～20cm soil layer, the change of slope cropland total phosphorus impact by slope drainage engineering was not big, but for forestland, grass and ladder flat land the influence increasing of the total phosphorus content by slope drainage engineering was significant;20～40cm soil layer, the changes of slope cropland total phosphorus effected by slope drainage engineering was not significant, but the forest land, grass and ladder flat land total phosphorus increased by slope drainage engineering was obvious.0-20cm soil layer, the impact by slope drainage engineering was not big changes effective phosphorus on the grass, but increasing of the effective phosphorus content in forest land, ladder flat and slope cropland was significant;20～40cm soil layer, the change of forestland and grass effective phosphorus by slope drainage engineering was not significant, but the effect of ladder and the slope cropland increasing of effective phosphorus was obvious.0～20cm soil layer, the influence on total potassium content of forestland and grass increased by slope drainage engineering was significant, but the ladder flat land and slope cropland total potassium content increase effect by slope drainage engineering was not significant;20～40cm soil layer, the total potassium of grass change by slope drainage engineering was not significant, but the forest land, ladder flat land and slope cropland total potassium content increased by slope drainage engineering was obvious.0～20cm soil layer, the change of forestland rapidly-available potassium impact by slope drainage engineering was not big, but on the grass, ladder flat land and slope cropland rapidly-available potassium content increased by slope drainage engineering was marked;20～40cm soil layer, the effect on ladder flat land and slope cropland rapidly-available potassium change by slope drainage engineering was not significant, but the forest land and grass rapidly-available potassium content increased by slope drainage engineering was obvious.(2) The improvement of soil physical property by slope drainage engineering was not obvious.Soil bulk density of slope drainage group was bigger than the control group. Each sample main influence factors of Each sample soil moisture content was land use type, slope and slope shape also has a large effect on its.The influence of these factors were over the influence of soil porosity. Slope drainage engineering on the sample surface capillary pore and under the top layer of capillary pore development form has a role in promoting in a short period of time. To various soil fractal dimension calculation comparison found:0～20cm soil layer, except forest land, the rest of the three types of the clay content in the plot for the slope drainage group> the control group;20-40cm soil layer, the samples of various land use types in clay content is shown as the control group> slope drainage group. Slope drainage engineering reduces the slope surface of fine particle soil erosion in a certain extent. The permeation properties of the study found that slope drainage engineering improved permeability of grass and ladder flat land, had not very good effect on forest land and slope cropland. Field in-situ permeability experiment showed forest land permeability coefficient of Slope drainage group was greater than the control group. Ladder flat land permeability coefficient of slope drainage group was smaller than the control group. The Grass initial permeability performance of slope drainage group was greater than the control group, but the stability permeability of the control group was greater than the slope drainage group.(3) Slope drainage project has an effect on reducing soil loss.Slope drainage engineering of forest land soil conservation effect was obvious, the specific performance in increased by0～20cm soil layer soil particles, relatively reduced the loss of20～40cm soil layer soil particles. Grass soil loss of slope drainage group was more serious than the control group; relatively effect of slope drainage engineering to reduce the loss of grass soil particles was not obvious. Slope drainage engineering in reducing ladder flat0～20cm soil layer soil erosion effects was obvious. Slope drainage engineering of slope to0～20cm soil layer soil conservation function was very obvious.