CHANGES IN CHEMICAL PROPERTIES OF MINE SOILS IN A RECLAMATION CHRONOSEQUENCE UNDER NEEM PLANTATIONPreeti Singh, Shankar Ram, Yogesh Pal, M. K. Prajapati and A. K. Ghosh
Mining is an important economic activity of our country fuelling our economic growth also leaves a serious impact on top fertile soil, ecology and vegetation as a whole, producing a lot of overburden that exacerbates the local environmental degradation and livelihood insecurity and hence need to be reclaimed. The present study attempts to assess the changes in chemical characteristics of overburden soil brought about by reclamation through planting trees. Soil samples were collected at two depths (0-15 and 15-60 cm) from overburden areas under different periods of reclamation (<1, 7, 10 and 25 years) under neem plantation in the Gevra opencast coal mine project, the largest coal mining project in Asia. The samples were analysed for chemical properties and compared with the natural forest of adjoining areas. The pH of the overburden dump was acidic (5.94) in the surface layer but became almost neutral (6.38) after 25 years under neem plantation. The electrical conductivity also decreased from 0.07 to 0.01 dS m-1 in the top layer and became similar to the reference site. Organic carbon improved from 0.10 to 14.90 g kg-1 in the top layer and 0.01 to 9.80 g kg-1 in the subsurface layer and was significantly more than the reference sites. Available P in the fresh dump was higher than in the reference site and showed improvement from 15.70 to 33.48 kg ha-1 during 7 to 25 years of reclamation in the topsoil and 8.35-30.37 kg ha-1 in the subsoil. Available potassium was low in the fresh overburden than native forest soil but improved from 13.80 to 127.48 kg ha-1 during 7 to 25 years under neem plantation and similarly in the subsoil but was still in the low to medium plant available range. Plant available micronutrients viz. iron, manganese zinc and copper content increased both in the surface and subsurface overburden dumps with increase in the age of restoration and was generally higher in the surface than subsurface soils. The heavy metal contents were low in the soils studied and hence did not pose any restriction to the reclamation process.
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