Ben Zumeta wrote:Seems to me biochar's main climate change mitigation claim is storing carbon and nitrogen in the soil. This is what hugelkulture does anyways without putting out the burned carbon or other pollutants.
From a plants perspective, a piece of dead wood is like a pioneer finding an abandoned city with all it's infrastructure largely in place (the vascular ire of the tree and its fungal occupants). Would it be better to find an abandoned charred city? I am no plant, though I have taught about fire ecology in the west, and it seems hard to imagine it benefiting most plants. I imagine it would benefit fire associated plants that tolerate the associated alkalinity, but calling it a universal answer seems like a marketing pitch. If your hugels burn by natures whim, then you still have biochar, which would mitigate the disaster, but it seems a waste of energy and fungus to burn wood instead of bury it.
Marco Banks wrote:You are looking to char the wood, not burn it. Big difference.
If you start a fire in a trench, you will need a way to seal off the oxygen from the fire once the wood it sufficiently charred. You want it to build a great deal of heat in a low oxygen environment so that the wood gasses off, but he majority of the carbon does not actually burn. Google charcoal making techniques --- people have been doing this for a long long time (which is the #1 reason for deforestation worldwide --- charcoal production). I know that there is a way to bury a burning pile of wood and then poke holes down into the pile to allow for a bit of air to get to it. Smolder is good. Open combustion is bad.
Rufaro Makamure wrote:We have started working on the zai pits in preparation for the farming season. We decided to do the holes ourselves (i.e. the lady staying at my mum’s plot and myself), since I now have the time. The ground was very hard, it was practically impossible to dig the whole place. We have resorted to pouring water as we re-dig the holes and the rate at which the soil absorbs the water is pretty amazing so this is making the work a lot easier. We are on day four of digging and we did half the area. This experience revealed the reason why the zai pits are not common, the digging is no joke. It is proving to be a bit unsustainable, to maximize value for time and effort farming this way. I am imagining where a struggling mother who has a responsibility of feeding her children, who does not have an easy water access, which is the bulk of the group I am trying to focus on, will get the time and energy? The method is definitely beneficial, its sustainability is the one I question in terms of its labor demands. Is there any simple tool (cheap) used when making these holes other than hoes and picks, because I fear that this concept might be perfect theoretically or for people who can outsource labor or in our case, families who have water readily available. I actually thought this method would be relatively affordable for a financially struggling family. If there is a different way of doing the zai pits please let me know. I know we have managed to prove that the zai pits definitely give a better yield, but it is not enough since it demands so much labor, time and energy. The zai pit concept managed to draw so much attention, the next step is to find a smarter way of preparation of the field and this might get people to eagerly do this (who knows, we might stop concentrating on just yields and start focusing on issues like climate change, soil regeneration... etc. as a community). We are going to wait so that we see how many of our neighbors will go the zai pit way this farming season.
Kaiwiki Clay wrote:At this cost, it is not even close to economical for carbon sequestration - guilder trees being by far the better alternative. But I've had good resultsso far applying char at about 1 gallon (maybe 5 lbs?) per 10 sqft. I'm on heavy tropic clay. Hugelkulture, even in the tropics where organic matter volitalizes so quickly, is the much better option for carbon sequestration. The recent trend towards char as a solution to global warming is total bs. It's just toexpensive unless subsidized by machinery. We have been discussing the option of a power-producing biochar machine that can char otherwise nearly worthless eucalyptus plantations (talk about a boondoggle!) something like a mobile 40ft container that takes in logs and produces power and char. But the startup cost would run into the millions for such a project.
Having made a few yards of char myself by the deep pit method, I can say it's a lot of work. Biochar vs hugelkulture = hugelkulture wins in terms of food produced per effort, at least in the short term.
Having said that, I've never seen mycellium take off like a 50/50 mix of char and compost. It's just wild! I mixed compost, char, and bonemeal and let it sit a few days with damp cardboard covering the whole thing. Pull back the cardboard and wow! White fuzzy growth all over. I then used this for veggie beds and seedling starter mix, with very good results. Im not sure if the effort that goes into the proccess is worth it when I could be hugelculturing or just chipping the wood into mulch, but the idea that the char could stick around for hundreds of years is pretty appealing.
Biochar: lots of hype, lots of work, good results. Is it worth it? Eeeeeh. Marginally so in the tropics, probably not in temperate climates where humus sticks around for centuries anyway. But it sure is fun to make a soil mix that grows so well!
Now a mulching machine that burned waste wood to make char and powered a chipper to make mulch/compost with the extra heat...expensive but probably worth the capital?