Amelioration Of Weathered Coal On Soil And Vegetation Restoration In Open-Cast Mine Area With Different Freezing-thawing Process And Water Content

Soil structure destroyed, nutrient losing and other environmental problems are caused by mining. Land restoration is considerable, which is destroyed by mining industry in many countries. Therefore, attention should be focused on restoration of the degraded ecosystem, including soil pollution and remediation, land use, and soil protection.At present, land ecosystem reconstruction has gotten notable achievement, through different restoration measures. Soil structure is still not recovered. For this purpose, soil productivity reconstructed is needed. There are many good ameliorants and measures aiming at farmland soil amended, as it is restricted by many problems in mined area, such as the large scale land area, outlay, and management, etc. The amended measures are different with which applying in farmland. As produced with special environment conditions, weathered coal has low thermal efficiency. It is usually deserted in the adjacent and gradually accumulates to solid wastes, causing various environmental problems in China. But it is full of regenerated humic acids, which could help to form soil structure and recover soil productivity.The study is based on different amended measures of weathered coal on soil physical and chemical properties, soil enzyme activity, and soil nutrient, which choose weathered coal as remediation medium. The aim of this paper is to investigate the infection of weathered coal on mining area soil restoration with different freezing-thawing cycles and water contents in view of the climate of North China. So that best practices can be identified and used to guide future efforts. The main studied are: (1) Amelioration of weathered coal on soil physical and chemical properties in open-cast mine area under freezing-thawing process and water content; (2) Amelioration of weathered coal on soil physical, chemical properties and enzyme activities in open-cast mine area with vegetation restoration under different water content; (3) Amelioration of weathered coal on soil physical, chemical properties and enzyme activities with vegetation restoration under freezing-thawing process and water content.The main findings are summarized as follows:1. Results showed that applying weathered coal could efficiently amend soil structure in mining area, improve the content of soil nutrient, and promote soil enzyme activity. It reported that the maximum of weight percent of soil aggregates was 95.00%; the content of soil humus was 4-5 times of the mined soil, which was not amended. Amelioration of weathered coal on soil properties with vegetation restoration was studied in this research. Results showed that the maximum of weight percent of soil aggregates was 82.55%; the content of soil organic matter was 55%-144% higher than the experimental design in advance; the content of soil humus was 0.25%; maximum of urease activity was 0.132(NH₄-N mg/g/24h), 74% higher for the contrast. It showed that the maximum of weight percent of soil aggregates was 95.80%, and content of soil humus was 0.23%, after freezing-thawing process. Maximum of urease activity was 0.181(NH₄-N mg/g/24h), which was 88% higher for the contrast.2. It indicated that suitable water content is important for soil properties, and there was significant difference with different water contents. Weight percent of soil aggregates was 39%-48%, when water content was 10%, half of that of water content 15% or 20%; content of soil humus was 5 times of the none amended, when the water content was 10% and 15%, and 4 times when the water content was 20%. It showed that weight percent of soil water-stable aggregates, which water content was 15%, was significantly higher than that water content was 5% or 10%; with the same content of soil organic matters, soil humus content reached the maximum 0.25% when water content was 15%, it was 19.0% and 8.7% higher for that of water content 5% and 10%. After freezing-thawing process, it showed that weight percent of soil water-stable aggregates, which water content was 10%, was significantly higher than that water content was 5% or 15%. In conclusion, water content was a key factor in mined soil restoration, which should be regarded in restoration process.3. The selection of plant types was the key factor of vegetation restoration in mine area, which accorded to local weather and soil conditions. Results indicated that Alfalfa (Medicago sativa) was fit for the local conditions, and could be used in vegetation restoration. Soil physical, chemical properties, enzyme activities and vegetation restoration, of which planted Algonguin (Medicago sativa), were much better.4. Weather condition was an important natural factor, which could determine the local ecosystem. In the study, freezing-thawing process, as an abiological stress, significantly affected many soil properties such as soil aggregates, soil organic matters, CEC, total N, available P, available K, Catalase activity, invertase activity, and urease activity.The aim of this research is to investigate the infection of weathered coal on mining area soil restoration with different freezing-thawing cycles and water contents; in view of the climate of the open-cast mine. So that best practices can be identified and used to guide future efforts.