The Soil Fertility Quality Evaluation Of Coal Mining Area In The Northern Shaanxi

Coal is the main energy material in our country. In recent years, with the large-scale development and utilization of coal resources, especially the unreasonable development and utilization of the coal mining, the coal mine area's environment, geology and ecology have been severly damaged, threating the sustainable development of social economy. And the accumulation of a large number of coal gangue, gobbing and the landing of harmful gas and flyash lead to the soil problems become an prominent issue to be settled, which needs to evaluation the soil environmental quality, and to provide theoretical basis for soil restoration and ecological reconstruction. This article selects the three coal mines of Shenmu mine areas in northern shannxi: Da bianyao mine, Qing caojie mine and Ban dunyan mine, setting up a control plot at the same time, adopting the method of combining the field investigation and indoor analysis, analysis the indicators and characteristic of the mining area soil, to make the right evaluation of soil fertility, the main results are as follows:(1) Compared with the comparison areas, there is less soil clay content in three coal mine area. The content of soil sand has increased in Da bianyao coal mine and Qing caojie coal mine. The mining activities makes the phenomenon of sand soils occur in coal mine area. Coal mining destroys the soil structure, makes soil water content decreased, bulk density reduced, porosity increased, the soil loose. Three mine surface soil pH values ranging from 7.43~7.67, were lower than the control area, belonging to a neutral or slightly alkaline soil. Except total potassium and available potassium show a increasing tendency, other indicators of nutrient like organic matter, nitrogen and phosphorus show a decreasing tendency.(2) Adopting the comprehensive index method to evaluate the soil fertility of mining area, the comprehensive soil fertility coefficient of Da bianyao coal mine and Qing caojie coal mine are all less than 0.90, belong to the poor fertility level. The comprehensive soil fertility coefficient of Ban dunyan coal mine is 1.00, belongs to the general fertility levels. From the point of coefficient of each index of fertility, total potassium, available potassium of coal mine area has reached a fertile levels. The total nitrogen, alkali-hydrolyzale nitrogen, total phosphorus, available phosphorus in three coal mine area belong to poor fertility level, indicates the deficiency of nitrogen and phosphorus nutrient.(3) Compared with the control plot soil enzyme activity, soil urease, phosphatase, catalase, invertase and protease's activity are low, all are smothered by coal mining and other activities. Research the influence of soil enzyme activity to soil fertility using principal component analysis, the evaluation result is similar to the Nemerow index method. So the whole soil enzyme activity can be used to evaluate the level of soil fertility.