Here in western Oregon, we are heavy clay. The heavier the clay, the more helpful the char seems to be. I did a small hugel-char bed here. Haven't been very attentive to it, and it's only about a foot high. In the trench I put burnt wood. There are irises, oregano, thyme and comfrey planted in it. It didn't get any water through about a month of the summer, and things by then did look a bit dry. It is currently getting sort of starvation rations of water. I stand there for about 3 minutes with the hose on full blast -- not very impressive pressure -- twice a week. Everything but the comfrey looks good. The comfrey is getting eaten by something with 4 legs and fur, or wings and feathers, I suspect.
I think the charred wood I got from a clearcut slash pile. A non-technical way to find out if the char is reasonable quality is by washing your hands after handling it. If the black comes off pretty easily, there isn't much tar. That's the good stuff.
Plain char, smaller and completely burned is good too. I like a mix of sizes of char for mixing in the soil, I make my own (150 gallons this year and used 2/3 of it), and mostly it's 1 inch diameter or so. I may want to sift/grind a little for beds that might grow carrots.
I'm not sure how much to steep the char, don't put it with dry manure; expect it to absorb some moisture. I have a friend who gets char from slash burns and puts it in a barrel with whatever: chickenpoop, dead fish, urine and a bunch of water. She pulls it out when she is planting.
I'm a lazy bum, and I just lay mine on top of the ground, mulch over it and let the bacteria colonize it. If you put it IN the ground, definitely charge it. Haven't seen any issues with my method.
Try it, you'll like it!
Intermountain (Cascades and Coast range) oak savannah, 550 - 600 ft elevation. USDA zone 7a. Arid summers, soggy winters
My soil is also heavy clay. I make charcoal and use it in the base of wicking beds and in compost. Based on this experience and plenty of reading the literature on biochar, I suggest;
1. Charcoal that you gather after forest fires will do little on its own to improve clay soils or any soils for that matter.
2. Mixing with manure will be better but there will be more benefit from the manure than the charcoal.
3. Composting the manure, charcoal and other "browns" will greatly improve the nutritional and soil conditioning value of the individual components.
4. The composting process is improved by the addition of charcoal with a higher retention of nutrients especially nitrogen.
5. Grinding lumps of charcoal is highly desirable but wild fires do not produce perfectly charred pieces. Uncharred, woody bits resist grinding.
Now for the disclaimer; I am still learning how best to use biochar-enriched compost with clay. Best results so far are in compost only in raised beds. The finer particles of biochar provide structure to the compost. Clay would do the same and add minerals but for various reasons, top dressing or attempts to incorporate the compost in the clay have not worked well.
Sheri - I've been making biochar for a while and often end up with partially burnt stubs and harder lumps. Personally I don't bother crushing or grinding char that I make. I've found that plants force their roots into even relatively large lumps of char. When you pull a plant up the roots often have chunks dangling from them. My beds are as close to "no-till" as I can get, using lots of mulch materials. Chunky bits don't bother me because I don't care about digging or turning the soil.
I say collect some, spread it thinly on the top of the beds and top dress with some other mulch/compost. You can add more in later years if you feel the soil could cope with it.
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I had another idea this morning. There is a lot of ash - probably more ash than even charred wood. What are your thoughts on using the ash?
If the wood is so hard to grind up then maybe this would be ideal for a compost pile?
Sheri, must be the grinder in me as I prefer to use shredded material to make hot compost. I am not familiar with ash but expect large pieces would take a long time to decompose. Have you thought about using wood and charred wood in hugel beds? Mind you, clay still behaves like clay if it sits on a pile of wood without any added organic matter.
Yeah, but how did the squirrel get in there? Was it because of the tiny ad?