Scientists believe that biochar, the partially burned remains of plants, has been used as fertilizer for at least 2,000 years in the Amazon Basin. Since initial studies published several years ago promoted biochar, farmers around the world have been using it as a soil additive to increase fertility and crop yields. But a new study casts doubt on biochar’s efficacy, finding that using it only improves crop growth in the tropics, with no yield benefit at all in the temperate zone.
“We saw a huge boost for crops grown in the tropics, but zero results for crops in the temperate zone,” said Dr. Bruce Hungate, Director of the Center for Ecosystem Science and Society at Northern Arizona University and co-author on the study. “Given all the talk about the benefits of biochar, we were really surprised.”