Soil carbon development in rejuvenated Indian coal mine spoil

The impact of mine spoil on the landscape is significant, as excavated rock-debris is commonly disposed in heaps that blanket the original land surface. Spoil heaps destroy the original soil habitat releasing soil-bound carbon, which is difficult to re-estate when mining operations cease and restoration begins. The present work follows the development of vegetative cover on a coalmine spoil tip in India over a period of 19 years following restoration. The potential of re-vegetated the mine spoil to imbibe carbon is examined through the development of above- and below-ground biomass development. It was observed that the soil organic carbon and microbial biomass carbon (MBC) significantly increased with re-vegetation age, with above ground biomass increasing by 23 times, and belowground biomass increased by 26 times during the period of study. Soil organic carbon and MBC increased by 4× and 6.6× times, respectively. The average calculated annual carbon budget was 8.40 T/ha/year, of which 2.14 T/ha was allocated to above ground biomass, 0.31 T/ha to belowground biomass, 2.88 T/ha to litter mass and 1.35 T/ha was sequestered into the soil. This work has shown that the development of biomass following the restoration of mine spoil was significant and that considerable quantities of carbon were stored in above and below ground plant matter, and in the soil itself. It is concluded that appropriate restoration strategies can be used to rapidly establish a viable, healthy and sustainable ecosystem that imbibes carbon into former mine-impacted land.