Biochar had minor effects on yield, quality, and water availability of irrigated alfalfa, corn, and wheat

Abstract

Abstract One approach to water optimization in agriculture is to increase soil water retention. A soil amendment that has received attention for its ability to increase soil water retention is biochar, the remaining biomass after high‐C materials have been pyrolyzed. Two studies were conducted in Utah at two sites each during 2018–2020 to evaluate how a fast‐pyrolysis wood biochar influenced the productivity and crop quality of irrigated alfalfa ( Medicago sativa L.), corn ( Zea mays L.), and wheat ( Triticum aestivum L.) along with soil water tension. One study included a single biochar rate of 22 Mg ha −1 at two levels of irrigation (full vs. partial), where soil‐incorporated biochar increased silage corn yield by 12% in 2018 and reduced yield by 10% in 2019. Topdressed biochar had no effect on alfalfa yield from 2018 to 2020 in either irrigation rate. The other trial had six to seven biochar rates (0–67 Mg ha −1 ) plus the addition of wood chips at a single rate (22 Mg ha −1 ) at one site. This trial displayed a yield decrease of 0.01 Mg ha −1 of wheat grain for each additional 1 Mg ha −1 of biochar applied; however, there were no effects on silage corn production. Data obtained over 10 site‐years showed minimal effects from this type of biochar on crop yield, quality, or soil water tension, leading us to conclude that this wood biochar was not an effective tool for enhancing short‐term crop production or conserving irrigation water in arid agriculture.