Vermicomposting converts fly ash to enrich soil fertility and sustain crop growth in red and lateritic soils

Large scale generation of fly ash (FA) from thermal power plants is now posing an acute global disposal problem. There are three major constraints for agricultural use of FA: (i) low nutrient availability, (ii) heavy metal toxicity and (iii) slow rate of degradation of FA in soils. In the present investigation, various combinations of FA and organic matter (OM) like cow dung were allowed to interact with and without (control) epigeic earthworm (Eisenia fetida). Vermicomposted materials were applied to soil samples collected from a typical red and lateritic soil zone of India and availability of three nutrient elements were assessed at periodic intervals. Vermicomposted FA when applied to a red and lateritic soil not only enhanced availability of three major nutrient elements viz. N, P and K but also helped to maintain low solubility of heavy metals like Pb, Cr and Cd in soil. Advantage of vermicomposted FA and organic matter (1:1) @ 10 t ha−1 in potato cultivation was evidenced by significant increase in crop yield due to enhanced soil fertility and reduced risk of heavy metal toxicity.

► Vermicomposting enhances nutrient availability in fly ash.
► Solubility of Pb, Cr and Cd in fly ash is reduced.
► Vermicomposted fly ash improves fertility of laterite crop land.
► Vermicomposted fly ash substituted chemical fertilizer to a considerable extent.