Assessment of Soil Water Conservation with Biochar in Oregon Cropping Systems

Biochar, a carbon-rich by-product of energy production, has received growing attention as a soil amendment that can improve soil structure and crop production, as well sequestering carbon. In this study we evaluated the potential for gasified wood and grass biochars to improve soil water retention in a range of Oregon agricultural soils. Using laboratory measures of moisture release we showed increases in plant-available water at amendment rates as low as 1% by mass in most soils. Using a model of field hydrological balance (SPAW), we extrapolated from laboratory measures to estimate the potential benefits of biochar amendment under dryland and irrigated field conditions. Under both current and projected climate conditions, biochar provided modest benefits for soil water conservation when applied at economically-feasible rates. In combination with other cultural practices, gasified biochars can provide benefits for drought adaptation.