Jay Fitzgerald, a "Seasteading
" guru who swallowed the anchor to start farming in Hawaii, has just posted the first year results
of his experiments using biochar
to create terra preta
soils. So far he's learned a few things and guessed a few more, but overall he's very pleased. There's an earlier post on his thoughts and procedures here
"All in all the reports seem to bear true. I'd suggest one will see about a 20 to 30 percent growth yield over untreated soils. For those of us who intend to as much as possible function in the absence of(or minimal usage of) commercial fertilizers(organic or not) and follow a food forestry model, biochar is an absolute godsend and really makes it look much much more viable. As well, we've turned every invasive plant on the island into a valuable commodity." That observed yield increase is on very poor jungle soil, so not sure how applicable it is to soils that are already workable.
The basic idea is that fine charcoal (created on site from waste or invasive biomass) is churned into the soil to hold moisture and nutrients while serving as a carbon sink. It was discovered in the Amazon basin and believed created by farmers there between 450 BC and AD 950. There's a lot of interest and research in the carbon sequestration angle, particularly because it's cheap, easy and has the potential to do double duty in third-world farming. Assuming they have some excess biomass to start with, farmers could improve soils while pocketing a sequestration credit.
Anyone looking into this for local use?