Wednesday, December 24, 2008

Terra preta do haole and winter in Hawaii

It has cooled off a bit finally and a the rainy season has started a bit, yet the weather is significantly different than last year. The Ohia are just starting to bloom now--it was early November last season. The north Pacific has some business going on as those in Washington state are aware for sure. The ice will sometimes blow in high in the morning--as in the photo, and fall as a mist at dawn. Pretty spectacular.

Plugging away on the terra preta project, as it's a good project to mix in while getting rained off work. No information on how it works in the soil yet, as, of course, it isn't yet. But, I'm working away putting it into the soil on a regular basis. There are immediate changes one notices that I'll get to in a bit.

After doing the research one will find that the "bio-char" isn't something that one can just willy nilly sprinkle on. While small amounts may be advantageous, one needs relatively high loadings to get the real big effects that one equates with terra preta. That figure seems to be around 10% in the top foot or so of soil, in the aerobic zone. So, I'm assuming that one needs to put down at least 1 lb a square foot to be in the running, and that's a big project.

Not an insurmountable project, however, as in one run I make about 30 lbs of charcoal. It's not the sort of activity that takes a great deal of attention, so taking it on as a hit an miss sort of deal isn't a big problem. While the guava wood is nice, we're not shooting for a char like a hard fuel grade. Any old smaggy green will work if it has some cellulose in it. The soggier the material you process, the less complete a conversion you will get--in some ways that's apparently good. It's no big deal as if you have pieces in the mix that didn't completely burn you'll simply pitch them in to run the next batch.

It's simply a manner of lighting a fire in a barrel full of wood, and when it gets hot enough choking the air off so you get charcoal and not ash. There a little talent to it but precious little. In the process, however discover a few things about why it was initially done. First, you'll note that you're likely to be making the charcoal near your garden, and the process can make a fair bit of smoke. Especially as the wood is pretty wet the smoke is heavy, and it will blow all around the garden, in essence fumigating it. It may well be my imagination, but it seems it's done a pretty fair job of chasing the bugs off, and there's no reason to expect that it wouldn't. Stone age pesticide.

Secondly, once you apply the material, you find that you darken the soil appreciably. Of course, right? But the immediate effect is that the soil heats up a LOT faster in the sun and retains that heat. Higher earlier germination rates and a higher level of biologic activity can only result.

So, the big questions--is this an ecologically benign activity? We're going to hear a lot about terra preta from big institutions soon and it's worth asking before it gets rammed down our throats.

First, we have to admit--we are burning wood. Burning wood is bad for the atmosphere. Burning live trees is pretty questionable at any rate. The only way that terra preta is "green" is if it works--and that's likely a big if. The key is that you greate a soil so rich that it literally grows like an organism. Studies do show it can, and at a surprisingly high rate. Rather than the typical 1 inch a century in a wild environment that seems typical, the androgenic soils can grow at .5 inch a year. They do so by retaining and pumping down a lot of carbon which is near permanently sequestered. This is good. The data is incomplete, at this moment, but is perhaps the most encouraging technique I've seen in a long time, suggesting that it's actually a carbon negative activity, meaning there's less CO2 in the air when you're done, assuming you do the whole thing. At any rate if one were to cut a guava tree, char it, mix it in the soil, and plant some fast growing monster like a koa or monkey pod on the place, I doubt you could lose on that score.

Secondly, and key to my message in this forum--is terra preta a sensible survival option? Remember, we're assuming that a sensibly minimalist and self-sufficient lifestyle may well become necessary. I've assumed from the start that the biosphere is going to suffer widespread damage--and my goal isn't to save it, but rather encourage and personally create small "arks," if you will. From this perspective, terra preta is an obvious winner. To maintain my goal of being under a 3 acre footprint, I will need to consciously "eco-form" an anthropogenic environment that works at a healthier and higher level of functionality than it might left unattended, or, rather, merely tended by pigs and birds.


Things I've learned.

It's amazing what you learn by doing rather than theorizing.

Anyway, having worked in a whole bunch of charcoal into the soil now I've started to ask myself--why do I want this broke down? Isn't big chunks better than dust? In a tropical environ where rainfall abounds drainage is ofter a much bigger issue than fertility. . . I expect that a grain size much like that acetate shit they put in plants is about the place to be. It makes for quite a light and fertile soil very rapidly. Keeping it that way with annual loadings of new material that isn't mechanically degraded will contribute to the ultimate carbon load. In the mean time, however, there are near immediate effects to the ammendment.


Having significant char loads in test beds at this moment I can conclusively declare that the biochar works. The most noticable effect is that fertilizer needs are vastly reduced. In test patches in un-chared soil triple 16 is near ideal for most everything I have up here. With char in the ground the triple 16 is nearly lethally strong--exactly as advertised. Since the goal is to ammend soil while I can and rely on leaf mold once the potash in the world is all used up, it is clear that the char will be a huge help to avoiding soil depletion.

The ancient Hawaiians used char made from the false staghorn fern in the taro patches as a soil ammendment, by the way, and now so do I.


allensylves said...

Good to see you are testing out the terra preta. When I get to Puna in about two years I can find out from you all about how to make my raised beds the best way.

Anonymous said...

Merry Christmas Jay

Zachary Stowasser said...

I've heard it is hard to find good soil naturally on hawaii, so is this the method to build and improve? I've heard of biochar before but the way you describe it is inspiring! Thanks!

Bill Terry said...

I think that sawdust is used to make charcoal. Could sawdust be used to make bio-char? A 20 pound bag of charcoal costs about $10. Could this be use for a test. Some way to break it up, maybe a hammer. Some charcoal looks like pieces of wood. Am I on the wrong track.\