Productivity of Biochar–Amended Soils from Degraded Lands of the Semiarid Southwest US.

The potential of agricultural, forest, and degraded lands to sequester carbon from the atmosphere is a relatively small but immediately useful option for carbon storage. Currently in the semiarid Southwestern US, forest management and agricultural practices involve burning of residues to either eliminate fuel loads or decrease waste for disposal. Burning releases most of the carbon in these forms to the atmosphere as CO2, other greenhouse gases, and carbon particulates. Shredded or mulched waste that is buried in these soils decreases the immediate loss of carbon to the atmosphere, but loss is still significant over time as the material degrades. Conversion of the wastes to charcoal, and incorporating it in soils as biochar, avoids most of the carbon loss to the atmosphere while providing a more permanent carbon form in the soils. We tested the value of biochar amendments in reclaiming degraded land in an initial greenhouse study. Paired pots of soil and biochar-treated soil were planted with beans (P. vulgaris) and several parameters were monitored for the growing season, including water use efficiency, total biomass, bean biomass, and root mass. Overall, the biochar-amended soils performed better at water-use efficiency and biomass production than the untreated soils, and showed no adverse effects even when 25% biochar by volume was added. We are scaling this work to plot scale for testing not only the potential to increase productivity of marginal land in semiarid climates, but also as a means to permanently store large quantities of carbon in these soils.