It doesn't count as sequestering when the original input didn't come from the carbon dioxide in the air. In effect we are putting perhaps 1% of the fossil fuels

It doesn't count as sequestering when the original input didn't come from the carbon dioxide in the air. In effect we are putting perhaps 1% of the fossil fuels back underground. With biochar the land is improved for growing crops where as landfills are unlikely to be useable in any form in the near term.