Physico-Chemical Characteristics of Greening Substrate Used in Mining Slope Restoration and Its Optimum Mixture Ratio
China has abundant limestone mineral resources, which covers the areas of 13 × 105 km2. The intensive exploitation of limestone causes large area of mining wasteland, such as rock slope, and causes eco-environmental damages, such as soil degradation and vegetation destruction. Greening substrate is a kind of “artificial soil”, which is suitable for plant growth and succession and is significantly important for vegetation restoration in the rock slope. The purpose of this paper was to study the physical and chemical characteristics of greening substrates and its optimum mixture ratio. Based on the principle of “waste control by waste”, 49 groups of greening substrates with different mixture ratios were made from coal ash, soil, activated sludge, slag, super absorbent polymers, urea and wheat straw using the orthogonal test (L49 75). Festuca arundinacea was used as an experimental plant, and soils from an artificial forest were used as a reference. Results indicated that the greening substrate contained lower contents of pH and bulk density but higher contents of water, electrical conductivity, organic matter, total phosphorus, total potassium, available phosphorus and available potassium than the control soils. Compared to the control soils, the greening substrate had more obvious aggregate structures according to the analysis of scanning electron microscope. The content of sludge in the greening substrate significantly affected the characteristics of water and fertilizer condition, acidity and alkalinity, salt density and seed germination. The optimum mixture ratio of greening substrate is super absorbent polymers (0.7%), sludge (9.7%), coal ash (38.9%), soil (38.9%), slag (9.7%), urea (0%) and wheat straw (1.9%) according to the range analysis. These results suggested that the greening substrates with reasonable mixture ratio can supply good condition of water and fertilizer, and are suitable for plant growth.
KeywordsMining slope Vegetation restoration Greening substrate Fertility Scanning electron microscope
This study was financially supported by the National Natural Science Foundation of China (No. 41371501, No. 41502241), Doctor Program Foundation of Henan Polytechnic University Grant (No. B2013-069), Science and Technology Research Project of Henan Province (No. 172102310354) and Technological Innovation Team of Colleges and Universities in Henan Province of China (No. 15IRTSTHN027).
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