Study Of Artificial Grassland Establishment For New Soil Of Typical Mining Area Impact

Opencast mining activities drastic changed the environment of terrestrial ecosystems and led to serious land degradation. Opencast mining activities formed a large area of dump and occupation of farmland which affected animal and plant habitats. Besides, they also caused serious soil erosion which was a serious threat to the ecological environment. Therefore,recovery and reconstruction of dump ecosystems became the focus of ecosystem reconstruction in the mining areas. Land reclamation and revegetation were the basic works of dump ecosystem restoration and reconstruction. In order to explore the influences of different types of artificial grasslands to soil physical and chemical properties and soil infiltration as well as the effects of artificial grasslands establishment on rainfall-soil water conversion process. In our study, we studied on different artificial grassland what planted on the dump of Yongli coal company, Erdos City, Inner Mongolia Autonomous Region. The 10 types of artificial grasslands were Medicago stative, Lespedeza davurica, Astragalus adsurgens, Agropyron mongolicum, Hedysarum scoparium, Bromus inermis, Hedysarum mongolicum, Agropyron mongolicum + Artemisia desertorum, Astragalus adsurgens +Artemisia desertorum and Medicago stative + Bromus inermis grassland and bare soil as the control. We surveyed the biomass, soil water content and soil water infiltration capacity of different artificial grasslands and determination of the physical and chemical properties of soil through field investigation and laboratory analysis. Results showed that:(1) Artificial grassland could decrease soil bulk density and improve soil porosity.Artificial grassland establishment could decrease soil bulk density compared to bare soil.0-10 cm layer soil bulk density of Agropyron mongolicum + Artemisia desertorum,Astragalus adsurgens + Artemisia desertorum and Medicago stative + Bromus inermis mixed-sown grasslands were lower than Agropyron mongolicum, Astragalus adsurgens,Medicago stative and Bromus inermis singled-sown grasslands. 10-30 cm layers soil bulk density of gramineous grassland were higher than leguminous grassland; artificial grasslands could improve soil total porosity and capillary porosity, soil porosity at depth of 0-10 cm in mixed-sown grasslands were higher than that in singled-sown grassland, soil porosity at depth of 10-30 cm in leguminous grasslands were higher than that in gramineous grasslands.(2) Artificial grassland could increase soil organic carbon and improve soil pH.Compared with the bare soil, artificial grass could significantly increase the soil organic carbon content, the organic carbon content decreased with the soil depth increasing.Significant difference was found in soil organic carbon content under different artificial grasslands. Shrub had a greater influence on the soil organic carbon content of leguminous grasslands than that of gramineous grasslands; grass-legume mixed sowing could significantly increase the soil organic carbon content of gramineous grasslands. Artificial grasslands had higher soil pH value than bare soil in all soil layers. Soil pH value of legume-shrub and grass-shrub mixed-sown grasslands were higher than leguminous and gramineous singled-sown grasslands, while soil pH value of grass-legume mixed-sown grassland was lower than leguminous and gramineous singled-sown grasslands.(3) Artificial grassland could improve soil infiltration capacity and increase soil water content. In June, the artificial grassland soil moisture content of different soil depth were significantly lower than that of bare soil, soil water content increased and then decreased with the soil depth increasing. The soil water content of gramineous grasslands were higher than other grassland types; in August, the artificial grassland soil water content were higher than that of bare soil, soil water content of legume-shrub mixed-sown grassland was higher than leguminous singled-sown grassland, soil water content of legume-grass and grass-shrub mixed-sown grasslands were lower than gramineous singled-sown grassland; in October,0-30 cm layer soil water content of artificial grasslands were higher than that of bare soil,while 30-50 cm layer soil water content were lower than bare soil. Compared to bare soil,artificial grasslands significantly improved soil infiltration capacity. Soil infiltration rate of artificial grassland were changed with the growing season, in vigorous growth season(August), the soil infiltration rate of gramineous grassland decreased and that of leguminous grassland increased, different mixed modes had different effects on soil water infiltration capacity, shrub or leguminous plants mixed with gramineous plants could improve soil water infiltration capacity of gramineous grassland, while shrub-legume mixed-sown grassland would decrease soil water infiltration capacity of leguminous grassland.(4) Evapotranspiration of artificial grasslands were higher than that of bare soil.Evapotranspiration influenced by rainfall. Evapotranspiration of Legume-shrub and grass-shrub mixed-sown grassland were lower than that of leguminous and gramineous singled-sown grassland, Evapotranspiration of gramineous grasslands were lower than that of leguminous grassland. All artificial grasslands existed soil water storage deficit, the most serious soil water storage deficit in August. Compared with legume-shrub mixed-sown grassland, soil water storage deficit of grass-shrub mixed-sown grassland was more serious,mixed with leguminous plants would increase the soil water storage deficit of gramineousgrassland; the compensation degree of soil water storage deficit of artificial grasslands were less than 1, soil water was not completely added under the condition of natural rainfall.Mixed with shrub would decrease the compensation degree of soil water storage deficit of gramineous grassland, while the compensation degree of soil water storage deficit of shrub-legume and grass-legume mixed-sown grasslands were higher that of grass and legume singled-sown grasslands. Soil water use efficiency of artificial grasslands were different, soil water use efficiency of gramineous grasslands were higher than that of leguminous grasslands,compared to legume singled-sown grassland, grass-legume and shrub-legume mixed-sown grasslands had higher soil water use efficiency.The configuration of artificial grassland have an effect on soil physical and chemical properties, soil moisture and infiltration capacity. The soil bulk density, soil total porosity and organic carbon content of mixed-sown grasslands were higher than that of singled-sown grasslands. In vigorous growth season(August), soil water content of Astragalus adsurgens +Artemisia desertorum mixed-sown grasslands were higher than that of Astragalus adsurgens singled-sown grasslands. Besides, the soil water infiltration capacity of Astragalus adsurgens+ Artemisia desertorum grasslands were the best, the evapotranspiration and the degree of soil water storage deficit of Astragalus adsurgens + Artemisia desertorum grasslands were lower than that of others mixed-sown grasslands. For the compensation degree of soil water storage deficit and water use efficiency, Astragalus adsurgens + Artemisia desertorum grasslands were better than others mixed-sown grasslands. From the effect of soil improvement and the sustainable utilization of grassland, Astragalus adsurgens + Artemisia desertorum mixed-sown grassland is the best configuration mode for improving the new soil of mining area.