Economics of biomass production on an abandoned coal washing settlement pond

Numerous surface mine reclamation studies have shown organic mulches to be beneficial for tree productivity. This study was established to determine if similar techniques would be as biologically successful and as economically efficient in the production of black locust (Robinia pseudoacacia L.) biomass on a highly acidic (pH 1.8) abandoned coal washing site. The study area was limed at a rate of 336.5 mtons/ha and fertilized with 336.25 kg/ha of 16-32-8. Organic mulches applied were hardwood bark, a mixture of bark, sawdust and manure, a mixture of sewage sludge and kiln dust, and a mixture of straw and manure. Tree performance was measured after three and six growing seasons. Economic efficiency was assessed using benefit-cost ratios. In all cases, biomass production under the control was statistically the same as or higher than that observed for any of the mulches. Benefit-cost ratios for biomass production under the control was always statistically greater than that for the mulches. In this case, the production of black locust biomass under the four soil amendments tested could not be justified by the substantially greater cost of their establishment.