Can Biochar Soil Amendments Enhance the Carbon Storage in Forest Soils?.

The unique chemical and physical properties of biochar make it a promising amendment to enhance carbon sequestration in soils. Sandy soils typically have low organic matter contents and dissolved organic carbon (DOC) from leaf litter, as it is easily degraded and leached from the system. One potential strategy to sequester this carbon in course textured forest soils is through the return of forest thinning materials as biochar. Therefore, the primary goal of this study is to determine if biochar soil amendments produced by pyrolysis of biomass from forest thinning for bioenergy can enhance carbon storage in forest soils. Ponderosa pine trees have been harvested, chipped, and dried to produce biochar at 300, 500, 700, and 900 °C. The biochar has been characterized for a host of physical and chemical properties including total C/H/O, ash content, surface area, cation exchange capacity, and pH. Saturated and unsaturated soil column leaching experiments, compared the DOC in the leachate of sand controls to forest soil. Additional analysis, using benzene polycarboxylic acids (BPCA) as molecular markers to evaluate transport of pyrogenic carbon versus native soil carbon is ongoing. The data suggest that biochar soil amendments can be an effective management strategy for reducing DOC leaching and enhancing soil carbon stocks.