Increasingly, though, they are turning all those husks and stalks into biochar that captures carbon and improves yields. Workers “charge” this biochar by soaking it in manure or other fertilizers,​​ then farmers add it to their fields. And our thesis is that you can increase food productivity, creating lots of jobs.”Some soils benefit more from biochar than others, though. “So that’s really where biochar comes in best, is in tropical soil.”Even if it’s not dramatically improving soil, biochar has serious potential as a negative-emissions technology. “If we’re talking just climate change mitigation, maybe just burying big piles of biochar is the way to go.”