Effects Of Coal Mining On Soil Environment And Microbial Restoration In Western Area Of China

Through the method of field monitoring, processing laboratory samples and analyzing data of the Bulianta and Daliuta in Shendong mining area, the variation of soil moisture and hydro-physical properties by coal mining in Shendong are studied, At the same time, the micro-environment succession rhizospheric soil caused by coal mining was studied, the physical, chemical, biological properties of rhizospheric soil are monitored and studied emphatically. According to the ecological destruction and the influence of vegetation caused by coal mining of Shendong, with the inoculation of arbuscular mycorrhizal fungi and the substances added artificially to promote microenvironment of rhizospheric soil and accelerate the ecological restoration of damaged mining. By means of combining arbuscular mycorrhizal fungi and water retaining agent in pot experiment, the combined effects on the growth and drought resistant of vegetation in water deficit mining area. The main conclusions of the study are as follows:(1)The soil moisture content decreased by cracked coal mining subsidence, the soil moisture of cracks and without cracks of subsidence area were smaller than that of nonmining area, In general, the rank of soil moisture content: cracked area < uncracked area < nonmining area. The fracture density and soil moisture content have a significant negative correlation, the less soil water content as the fracture density is bigger. when the crack width is greater, the greater loss of soil water before the rain falls; soil water loss rate in cracked zone is greater than the uncracked after the rain. Closed fracture in short term has little effect on recovery of soil water, recover soil moisture needs a long time after the settlement. Coal mining increases the soil evaporation, it is showed that the crack area> Subsidence> control area, soil evaporation in crack zone enhanced significantly. Different soil evaporation after different coal mining periods, soil water evaporation is larger in the development of cracks, soil water evaporation is smaller in water deficit period. Surface cracks and Subsidence can increases soil infiltration rate and infiltration rate, it is detrimental soil moisture retention with increasing the depth of water infiltration. Mining subsidence caused effect on soil hydro-physical properties, the increase of soil bulk density and soil porosity caused by subsidence and cracks may happen,and soil field water capacity and saturated water content decreased, soil water storage decreased, it has a negative effect on the growth of plants. With the extension of time, the soil bulk density, porosity and field capacity tend to recover,while the speed of recovery in subsidence area is fast but the fracture zone is difficult to restore in the short term.(2)Compared with that of the nonmining area, the soil bulk density of the plant rhizosphere decreased and porosity increased after coal mining, especially the influence is bigger during mining in one or two years, its value was similar to the undeveloped state with the exploitation of mining time. There are obvious changes in soil water storage and soil water content after coal mining subsidence. Which are significantly decreased after mining 1-2 years. soil field water holding capacity has been restored as the mining subsidence becomes stable gradually. the available phosphorus and potassium in soil, alkali hydrolyzable nitrogen concentration, total phosphorus, total potassium and part of inorganic salt ions afte mining was decreased, and the shorter extraction time is, the more decrease, the rate of decline slowed or rebound partly with the exploitation of time. as the extension of collapse time, some indicators can be restored to the state before the mining subsidence, gradually eliminate the influence on the growth of vegetation. At the same time, coal mining has certain effects on the mycorrhizal colonization and hyphal density.The change of rhizosphere soil microorganism of different vegetation variates significantly in response to mining. Different datas about sampling time show the number of rhizosphere bacteria decrease in different plant species after coal mining one year, However, the number has recoveried with the exploitation of time, and the recovery rate changes in different plants with certain volatility. The the number of fungi and actinomycetes in rhizosphere soil variates obviously, the discipline is different in different seasons and species. Compared with the nonmining area, the number increases firstly and then decreases on the whole, and the number of fungi in the soil gradually decreases with the exploitation of mining time, but still higher than the nonmining areas. Coal mining has a certain effect on the rhizosphere soil enzyme activity which changes in different species. The phosphatase activity reduces after coal mining and recoveries with the time prolonging. Invertase, urease also recovery and increase gradually as subsidence time extended. The coal mining subsidence has impact on soil Glomalin synthesis. The easily extractable Glomalin related protein in the mining area is significantly lower than nonmining area, there is negative impact on the growth of arbuscular mycorrhizal by coal mining.(3)In the mining subside area of Shendong mining area, arbuscular mycorrhizal inoculation was advantageous to the mining area ecological environment restoration. Arbuscular mycorrhizal inoculation significantly improved the survival rate of Hippophae rhamnoides, different treatment presented as + M > F.m> R.i > CK after 14 months, respectively increased by 24.2%, 18.2%, 8.1% than the control. The inoculation significantly improved the heightand crown amplitude of seabuckthorn, meanwhile, it also promotd the growth of seabuckthorn roots, which the root length, root projected area, root surface area, root diameter and root number increased significantly compared with the control treatment. The best inoculation effect was + M treatment, the second was the F.m treatment and the third was the R.i treatment. Mycorrhizal fungi could form well symbiotic relation with sea buckthorn in the non-sterile condition. Different inoculation treatments could increase the root colonization rate and hyphal density.Mycorrhizal fungi could improve the plant rhizosphere soil microenvironment. After inoculated with mycorrhizal, the quantity of bacteria, fungi, and actinomycetes increased. The number of bacteria, fungi, actinomycetes showed a clear seasonal variation. The rhizosphere soil enzyme activity increased with the inoculation treatments, and different rhizosphere enzymes showed different response to the inoculation treatments. Phosphatase activity of + M treatment was significantly higher than control after 2 months, while different inoculation treatments significantly improved after 11 months and 14 months. In different periods, sucrase activity and urease activity were characterized by the inoculation > control, and the effect of +M treatment was the best. Mycorrhizal also had a benefit to the soil nutrient cycling, and soil improvement, which was important for the ecological restoration of damaged area.(4)Good symbiosis could be formed between maize and arbuscular mycorrhizal, arbuscular mycorrhizal inoculation significantly improved maize biomass, plant height, ground diameter.Compared with non-mycorrhizal plants, the inoculation increased the plant water use efficiency by 117% and 24.6% respectively under drought stress and normal water supply. The SPAD value and soluble protein contents of maize plant with inoculation increased. Inoculation was also favorable for the increase of plant catalase activity. At the same time, under drought stress and normal water supply conditions, mycorrhizal inoculation significantly reduced the plant leaf proline, malondialdehyde content by 14.1%, 18.9% and 59%, 14.1% respectively. In conclusion, arbuscular mycorrhizal fungi can promote the growth of maize, relieve the adverse impact of drought stress on maize growth, improve the drought resistance of maize. Proper concentration of polyglutamic acid can effectively promote the growth of corn and increase the nutrient concentrations in plants. Generally,polyglutamic acid with concentration of 0.05mg/kg could improve the growth and drought resistance for corn.Polyglutamic acid has a good synergistic effect with arbuscular mycorrhizal fungi,and they could help the growth of corn,help corn to absorb the nutrient of aboveground and underground and enhance the physiological reaction and enzyme activity in leaves of the plant so as to protect the plants against the effects of drought stress injuries and improve its drought resistance.