Biochar can benefit your soil, but only if properly prepared prior to application. In November 2007, scientists at the USDA National Laboratory for Agriculture and the Environment (NLAE) in Ames, Iowa, began multi-year field trials to assess the effects of biochar on crop productivity and soil quality. Scientists amended almost 8 acres with biochar made from hardwood. Twelve plots received 4 tons per acre; 12 were treated with 8 tons per acre.
They found no significant difference in the three-year average grain yield from either treatment. Other USDA field and laboratory studies in Idaho, Kentucky, Minnesota, South Carolina, and Texas showed hardwood biochar can improve soil structure and increase sandy soils’ ability to retain water. But soil fertility response was more variable.
USDA scientists violated four key principles for biochar use: they used 1) bulk char, in one large load; 2) raw, uncharged char; 3) sterile, uninoculated char, with only a tad of microbial life; and 4) synthetic salt fertilizer, tillage, and other antibiotic practices.