Poultry Litter Biochar to Promote Reclamation of Surface Mine Soils.

Poultry litter from confined animal operations is an environmental liability because of the potential for water and air pollution. Although poultry litter is valued as fertilizer, the cost of shipping the bulky material can be prohibitive. One potential solution is to turn the excess litter into energy through pyrolysis producing poultry litter biochar (PLB) as a byproduct. Reclaimed surface mine soils typically require fertilizer and lime amendments to promote plant growth; both of these are present in PLB. One potentially negative component in PLB is the high salt concentration. Elevated salt concentrations have the potential to inhibit germination and soil microbial processes. Our objectives were to determine 1) the effects of PLB on soil chemical properties and forage yields of seeded grasslands, 2) the effect of poultry litter biochar on the relative size of three labile carbon (C) pools; Permanganate Oxidizable C, Microbial Biomass C and Hot Water Extractable C in a replicated field experiment on a mine soil reclaimed in 1998. Separate laboratory experiments were conducted to determine the effect of PLB on soluble salt and carbon concentrations and the germination of lettuce (Lactuca sativa), rye (Secale cereal) and birdsfoot trefoil (Lotus corniculatus). PLB contained large concentrations of acid soluble Ca and P (>2,000 ppm), Na (>5,000 ppm), and K (25,000 ppm). Seed germination of trefoil was inhibited at the lowest PLB treatment (0.5% w/w). Forage yields were significantly increased (40%) in the field experiment. Data on soil carbon pools are still being analyzed. PLB has the potential to increase the productivity of established vegetation on reclaimed surface mine soils. However, because of salt effects on germination, additional experiments would be needed to evaluate plant response to PLB at seeding.