Soil And Water Conservation Effect Of Engineering Measures On Granite Red Soil Slope

Erosion produced on slope of the southern hilly area has large area and strong harm,and then threats to regional ecological security and social economic development. The slope engineering measures have been proved to have good effect of soil and water conservation, but they are affected by the terrain, organic, climate, vegetation and other factors. Due to the diversity of the terrain, materials and law of the soil erosion, the implementation of the slope engineering measures did not show diversity and systematic. Research about the service life of the slope engineering measures has been reported seldom, and it’s difficult to calculate benefits. The study set three measures as fish-scale pits, level trench,Level-terrace and a control on granite red soil at Hetian town, Changting county,Fujian province. The experimental plot size is10*30m,and it faces west. Before the experience it has30%coverage of Dicranopteris dichotoma. we research runoff, sediment, soil physical properties, soil nutrient and sediment in measures with7.5m3excavated volume for each plot, and get conclusions as:(1) Three kinds of slope engineering measures can reduce the runoff effectively. Fish-scale pits, level-terrace, level trench can reduce23.53%,34.60%,38.14%of runoff contrasted to control district. Level trench has good and stability effect on reducing runoff; effects on fish-scale pits was unstable, and it range from5.56%to33.90%.The effects were not good while rainfall is large. The effect of Level-terrace reduced along with the increase of rainfall. In the sediment reduction, respectively, fish-scale pits and level-terrace can reduce19.14%,7.64%.Level trench did not play a community order of sediment control function.(2) Three kinds of slope engineering measures have great influence on soil physical properties. The range of bulk density was control> level trench plot> Level-terrace plot>fish-scale pits plot, while measures can increase sand content, and decrease silt and clay content. The surface sand content distribution of three measures was in the order of fish-scale pit>Level-terrace>level trench. (3) Three kinds of measures can improve water and nutrient status on the slope. Three kinds of measures can reduce the loss of nutrient on slop, while fish-scale pits have good protecting fertilizer effect. Total nitrogen, total phosphorus, alkali solution nitrogen, phosphorus and phosphorus, organic matter content were higher than the control by43.36%,38.99%,7.55%,336.52%,23.23%; level trench and level-terrace have improved the level of available nutrients in various parts of soil significantly, more than30%. By dealing with three measures the surface0-8cm soil water storage size followed by Level-terrace(16.63mm)>level trench(15.70mm)>fish-scale pits(15.57mm)>control (14.48mm), and8-15cm soil water storage size followed by level trench (18.54mm)> control(16.56mm)>Level-terrace(16.32mm)>fish-scale pits (14.31mm). With the increase in soil depth by dealing with fish-scale pits, soil water storage deficit degree increased, while it had uneven distribution. Level trench had strong recharge to soil moisture on deep.(4) In the slope of granite red soil, three engineering measures are differences in life and firmness. The life of the three engineering measures is in the order of level-terrace>level trench>fish-scale pits, but the soil conservation benefits is in the order of level trench>fish-scale pits>level-terrace. Nineteen fish-scale pits have been filled, accounting for24.7%of the total;36have been produced erosion gully at the lower part, accounting for46.8%of the total; and75%of the measures have been damaged of varying degrees, level-terrace produced erosion gully at central,and sediment deposition focused on the side of measures. Level trench measure is solid, and has not been destroyed, while20percent of the part is filled.