Biochar: Is It a Sustainable Solution to Dry Land Agriculture, Forest Soil Reclamation and Greenhouse Gas Mitigation?.

Biochar is the carbon-rich solid co-product of thermochemical biofuel production, which has been advocated as a soil amendment capable of sequestering carbon while simultaneously improving crop yields and ecosystem sustainability. The recovery of biochar from biofuel production systems and its use as an amendment in critical managed soils has the potential to increase economic returns, while improving environmental quality and enhancing the overall sustainability of the system. Our biochar research program, coupling advanced isotopic techniques to laboratory and, more recently, field studies in managed crop, grass and forest sites, aims to enhance our mechanistic understanding of biochar effects on the soil physic-chemical and biological environment. Our ultimate goal is to underpin the basic mechanisms underlying the potential beneficial effects of biochar to its application for carbon sequestration; food and fiber production in semiarid land and the recovery of degraded soils. Overall, our studies demonstrate that char additions to soil increases water retention and creates a better environment for the microbial community, particularly favoring gram negative bacteria. However, microbial decomposition of biochar only slowly consumes a small fraction of it, thus char still significantly contributes to soil carbon sequestration. This is especially true in soils with little organic matter, where biochar additions may even induce negative priming. In the laboratory char also decreased nitrous oxide emissions through reducing nitrate availability and increasing pH. Results from these and other recently established field experiments will be presented.