CHANGES IN PHYSICAL PROPERTIES OF MINE SOILS BROUGHT ABOUT BY PLANTING TREESPreeti Singh, Shankar Ram and A. K. Ghosh
Mining results in the formation of huge amount of overburden materials which results in soil degradation, pollution and loss of economic wealth. Reclamation of overburden soils by planting trees can stabilize the spoil and accelerate the pedogenic processes influencing soil physical, chemical and biological properties. Selected soil physical properties were studied during the reclamation of coal mine spoil under plantation and compared to reference sites to gauge the restoration of soil properties from their pristine values. Soil colour was grey in the original dump and changed to yellow brown after 25 years of reclamation. Gravel content decreased from 17.33 to 12.33% and clay content increased from 21 to 31% during the restoration process. Surface bulk densities decreased with advancement of the reclamation process from 1.57 to 1.40 Mg m-3, but were wide apart from cultivated soils (1.13 Mg m-3) and natural forest (1.10 Mg m-3) of the area. Porosity of the cultivated fields (48.39%) and natural forests (50.47%) were much higher than reclamation sites (35.93%) and showed decreasing trends with increasing depth. Water holding capacity however improved from 36.48 % under fresh dump to 44.59% under 25 years of reclamation and was near to the reference sites. Thus, most of the physical properties studied, showed improved over the years of restoration under plantation indicating advancement in the pedogenic process. Hence it may be concluded that planting trees is an excellent way of restoration of coal mine overburden dumps. However it is a slow process and takes a long time to attain equilibrium with the surrounding environment.
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