Biochar application on commercial field crops using farm-scale equipmen

Abstract

Commercial growers who wish to apply biochar to their field crops will need to use conventional agricultural machinery to amend large field areas. Biochar produced by fast pyrolysis of hardwood was applied at a target rate of 5.6 t ha-1 to a single swath (10 m x 100 m) in an agricultural field in Quebec, Canada, using a commercial lime spreader. Windborne losses of up to 30% biochar occurred during handling, transportation, and application. We recommend covering and moistening the biochar before spreading, avoiding surface application on windy days, or mixing it with other materials (e.g., compost, manure) to reduce biochar loss. The biochar-amended swath and an adjacent equally sized swath that received no biochar were harrowed. The entire field was seeded with soybean in the first season, followed by an oat-forage mixture in the second season, and forage in the third season. Soybean and oat yields increased by up to 20% with biochar. In the third season, forage in the biochar-amended swath had greater nutrient concentration and higher projected milk production when used as feed for dairy cattle, based on near-infrared spectroscopy analysis. The variable cost of applying biochar was an estimated CA$2,285 ha-1, indicating the need for a complete cost-benefit analysis of farm-scale biochar applications.