Study On Ecological Restoration Soil Matrix In Helan Mountain Coal Mining Area

The improvement of residual soil and the preparation of vegetation matrix in the dump of openpit coal mine are the basis and focus of ecological restoration and vegetation restoration in Chinese mining area.In order to solve the problem of difficult vegetation restoration caused by the lack of soil in the process of vegetation restoration of Rujigou Dafeng open-pit coal mine in Shizuishan City,Ningxia,this paper sampled and measured the soil physical and chemical properties of 9 samples of the eastern and external dump of Rujigou Dafeng mine in Shizuishan City,Ningxia and the forest and grassland soil with good vegetation growth around the mining area.Fifteen soil physical and chemical indexes were selected and divided into structural indexes,regulatory indexes and nutrient classification indexes,and combined TOPSIS model to construct the quality standard of ecological restoration and vegetation matrix in Helanshan mining area.Combined with this standard and the soil quality obstacle model,the quality problem of residual soil was diagnosed.Based on this,pot experiments were carried out to obtain the formula of soil matrix corresponding to different improvement purposes,which provided scientific basis for the utilization of soil matrix prepared by the same and similar soil.The main results are as follows:(1)The quality standard system and quality standard of vegetation matrix for ecological restoration of coal mining sites in Helan Mountain are as follows :(1)Structural indexes : loamy sand to silty clay loam(Ⅱ),sandy loam to clay loam(Ⅰ).(2)Regulation index : pH(Ⅱ8.45～8.55;Ⅰ7.50～8.45).(3)Nutrient index : total nitrogen(Ⅱ0.82 ～ 1.51 g/kg;>Ⅰ1.51 g/kg),total potassium(Ⅱ17.63～20.50 g/kg;Ⅰ> 20.50 g/kg;),available potassium(Ⅱ99.69～172.67 mg/kg;Ⅰ> 172.67 mg/kg),available phosphorus(Ⅱ5.00～14.83 mg/kg;Ⅰ > 14.83 mg/kg).(2)The muck clay content in the dump was too high,and the sand content was too low.The contents of total nitrogen and available phosphorus were too low,and the proportion of structural index obstacle was higher than that of nutrient index.The improvement of residue should give priority to the improvement of structural index,that is,the reduction of clay content,the improvement of nutrient,and the increase of total nitrogen and available phosphorus content.(3)The best formula of improving the muck structure is ’ 85% muck + 10% sand + 5% PHA’;and ’ 95% muck + 5% PHA + 0.06 g/kg ammonium phosphate + 2.35 g/kg urea’ is the best formula to improve nutrient content,which makes the content of total nitrogen and available phosphorus reach the first class standard.(4)For Medicago sativa L.and Elymus dahuricus Turcz,the comprehensive improvement effect of ’ 95% muck + 5% PHA + 0.06 g/kg ammonium phosphate + 2.35 g/kg urea ’ was the best.