Moisture Physical Properties Of The Soil Under The Several Vegetation Restoration Models And Its Improvement In The Opencast Coal Mine Dumping

Opencast coal mining will destroy the topography and the landforms, vegetation and reduce biodiversity, cause soil erosion. Opencast coal mine dump is a huge man-made landform which is piled up by a large number of coal mining debris. Mine exploitation destroyed surface runoff, the groundwater system is not formed in the dump field, and the regional annual rainfall is less and concentration. So the water becomes the main factor to limit the vegetation restoration in the dump field. Though the study on physical properties of the soil under the several vegetation restoration models in the mining area, we can explore the restoration of the soil under different vegetation patterns, and combine with the actual situation of the local conditions to select the suitable local vegetation restoration model. It can provide support for mine vegetation restoration that comparison of physical properties of soil moisture by the soil that Sandstone, fly ash and dump soil with different ratio.In this paper, we chosen Heidaigou opencast coal mine as the research object. We select the grassland, shrub land, shrub and wood mixed land, and wood land of the vegetation restoration models in the mining area on the dump platform and the 2 place of the natural restoration of grassland and shrub land was selected in the field of dump. We set 2 replicates in each vegetation type, and take the topsoil 0-20 cm soil back to the laboratory to study its moisture water characteristics by Soil water characteristic curve. We mixed the sandstone, fly ash and the soil from dump according to different proportion. The sample was loaded into the 100cm3 cutting ring by the bulk density of 1.35g/cm3 and Determined of soil moisture characteristic curve.Firstly, physical properties of the soil in the dumping of Heidaigou opencast coal mine is poor, including bulk density was 1.51g/cm3 and total porosity of averaged 42.39%, capillary porosity averaged 39.31%, non-capillary porosity was 3.39%, which is far lower than the topsoil which is 50 ~ 56% of total porosity and 8 ~ 10% of non-capillary porosity; saturated water was 28.51% and field moisture water consumption averaged 24.18%.Secondly, the physical properties of the soil under different vegetation recovery patterns have no different. Soil bulk density of wood land was 1.58g/cm3, which was closest to the new dump. Arbor, shrub and mixed forest, have no difference; the minimum is 1.47g/cm3; the non-capillary porosity of arbor and shrub mixed forest which is 4.35% is highest than others and arbor is lowest which is 2.74%. But all the vegetation recovery patterns is lower than the new dump; Shrub and woodland saturated moisture content is highest for 29.56%, the lowest was 26.13% of wood land.Thirdly, Gardner model can fit Soil moisture characteristics curve very well both the soil under different vegetation restoration models and different soil improved treatment.Fourthly, soil water holding capacity under different restoration mode is grassland> natural grassland> shrub land> wood and shrub mixed land> natural shrub land> woodland. Soil water supply property under Different restoration mode is that natural grasslands, natural shrub land, wood and shrub mixed land, grassland, shrub land and wood land. Effectiveness of soil moisture content is substantially no difference. After many years of vegetation restoration, the soil moisture of the dump soil has no obvious difference compared to the naturally disturbed soil. From the perspective of land reclamation and soil moisture characteristics, the vegetation reconstruction patterns in dump platform was suggested to focus on grassland.And fifthly, sandstone, fly ash can increase the soil water holding capacity, and the higher of the ratio, the stronger of the soil water-holding. Adding in sandstone resulted in decreased soil water supply capacity. Adding in the same proportion sandstone and fly ash increased soil water supply capacity. It can improve soil water holding capacity, and improve soil water resistance that using sandstone and fly ash for soil improvement.