Saturday, June 27, 2009

Biochar II

The initial garden beds I've established with biochar are getting close to a year old at this point, and I've got a bit of data and miscellaneous observations to report. The biochar I'm using is primarily charred guava, homemade in steel drums. I've probably at this point produced a ton or so of biochar. There's about 1 pound per square foot of it mixed in jungle soil that's on the average of 8 inches to a foot deep. That may seem like a high loading to some, but very high carbon contents are key to the game and one could go twice that, I'm sure.


Immediately but perhaps not obvious: Soil is black. It gathers and retains much more solar radiation. Germination rates are higher and faster.

Initially I was pretty concerned that the biochar was having a toxic effect on growth. Many of the plants were showing what appeared to be a nitrogen deficiency, slow growing, yellowed leaves, and puny. These effects have disappeared. I can project two reasons why this may be the case.

1) The clean charcoal is in the process of absorbing such nutrients from the soil, so a temporary scarcity is bound to occur.

2) One may produce a P-K surplus or imbalance where the majority of the plant growth is dominated by root growth. The plant eventually recovers and flourishes, but initially things look rough.

I'd suggest at this point not applying biochar to the soil directly, but rather applying biochar to a composting process--and then applying the whole mix of compost and innoculated biochar. This seems to produce much greater and immediate results.

Any casual observation of the microfauna levels in the treated soil as opposed to jungle soil will leave one with no doubts about the healthy effects of the biochar. Small fungi abound, and are not present in the latter. Clearly there's a great deal of aerobic activity(odor) where the jungle soil is so anaerobic in places it stinks like sewage.

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.

Over the next few months my goal is to move from the "concept farm" of perhaps 10000 square feet to about an acre and semi-commercial status. Proof of concept has really been had, and I'm pleased to be able to report that this sort of concept is unquestionably a do-able, sustainable, and profitable enterprise. Table taros will be a big part of that project and finally I've enough clean planting material to make that jump. So far, the primary crop out here is U'ala Piko sweet potatoes with a few others thrown in the mix. As much as possible no-till practice. Yields at 9 months are reliably .25 to .5 lbs per square foot. No pest trouble yet to report. Topdressing only with small amounts of 10-20-20 special and trace elements. Some lime applied, as well as clean wood ash. I harvest the sweet potatoes when they're large enough to start poking out of the ground. The chickens find them for me.

. . .and meanwhile most everyone out there is bitching about the terrible economy and that "the kids here have no future". . .


Shawn said...

Inspiring, as always Jay. My Piko cuttings from you didn't do so well- I think I cut them too short- but I have enough to build on. I like the idea of mixing in the biochar to the compost, and additionally I would argue that it would be a great immediate addition to my new beds that seem to take 6 months to get them into planting shape. Biochar to come soon here; I've got a barrel, just need to run out of excuses...

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