DEGRADATION OF LAND DUE TO COAL-MINING AND ITS NATURAL RECOVERY PATTERN

Extensive coal mining in the hill state of Meghalaya, north-east India has resulted in ecological upheaval of thousands of hectares of land. The land which is directly hit by mining operations like excavation a nd dumping of overburden and coal is converted into new habitats, call ed colliery spoils, which lack completely the soil structure and whose elemental concentrations are greatly altered. The areas like hilltops , hillslopes and cultivated and abandoned agricultural fields, which a re not directly hit by mining operations, though retaining their struc ture, are affected by deposition of coal particles through wind and se epage water. Both physical and chemical properties of colliery spoil s howed a returning trend to the characteristic pre-mined levels of the soil during 20 years of natural recovery. However, the nutrient levels were still either significantly (P < 0.05) less (N,P,K,Mg and pH) or more (Ca, Mn, Zn, Fe and S) in the 20-year spoil compared to the pre-m ined overburden soil. It is suggested that backfilling of the pits wou ld be a cost-effective technique to maintain the approximate original contour. Properly planned channelization of seepage water is necessary to stop the deterioration of soil quality in agricultural fields and low-lying marginal lands. This would not only restore the nutrient lev el but also the vegetation cover or coal-mining-affected lands.