I was thinking about where biochar would be most useful. David the Good's thread involving his video got me thinking about what qualities would tend to make biochar most effective. Obviously, the Amazon is a good start. What are the qualities that would make your site a good candidate?
1. Lots of rain, which will wash out the valuable minerals in your soil. The organic material housed in your biochar will hold onto them.
2. Acidic soils. The ash remnant will even it out toward 7.0, and the biochar housing allows the microbes to set it back right.
3. Poor draining soils. Drowning soils will stop your roots from being able to breathe, causing disease and death. Biochar drains well.
4. Heat! Lots of it. It will use up the organic material in your soil very rapidly, making it less rich.
5. Sand, rock, or extremely fast draining soil, which will limit the amount of fertility retained in your soil.
6. Deserts, because the diversity of plant life and organic material is so limited, it's hard for microbes to live on anything.
By this count, I have 3/6 here in PNW. What do you have?
Can you think of other characteristics of a site that should be added to this list?
I get the first three out of the six here on Skye: almost constant rain (we went 18 months a few years ago with rain every day!), acidic soil (very!), poor draining silty soil, (also compacted by sheep and goat feet over decades after having been ploughed for potatoes previously so very degraded). I do have a bit of a slope, so generally the water has somewhere to go (which I guess makes 4 then?). I don't do much intensive gardening, but what I do is mainly in my polytunnel; so less wet and quite a bit hotter. That's where I would like most to see an improvement, although having added compost including wood ash there over the years that's the best soil now anyhow.
I'm definitely thinking of trying some biochar this year, although haven't worked our how best to go about it. I have lots of twiggy prunings from my coppice wood, so that is my char starting point. I'm thinking of making a simple double barrel retort and making a few batches through the summer, but haven't worked out the best way to charge and distribute it yet.
I have the combo that Eino Kenttä and Eric Hanson describe. I can and have added lots of organic matter to the clay areas, but that can turn it into what's sometimes called a "muck" soil - just as suffocatingly wet, but it just doesn't dry as far to the "concrete" stage. My reading suggests that the biochar will help to lighten the soil - I could use a ton of it for that purpose alone.
If hubby will get the back hoe back on the tractor, I'm *really starting to think about choosing a safe spot for a biochar trench that will take long branches and English Ivy in an effort to multiply the amount of char I can make. It's a bit tricky as they keep messing with the burning regulations here - I understand they want to keep the particulates out of the air and many people burn poorly, but we're the exact combo of "too wet to burn/too dry to burn safely" with a narrow margin in between! My current method of small batch biochar in our wood stove really only gives me enough to add to my compost pile and duck housing intermittently (duck-shit inoculated biochar is my current experiment). I could easily use much more of it.
The reason I worded the question to include places where it is most useful is because I think it is more helpful in some places than in others.
I think we all know that Paul Wheaton is not very pro biochar for temperate areas. There are places where it wouldn't help as much. Going through the list, if I were in a place like Iowa before all the corn, Roundup, Gmos and soybeans might be such a place.
Dry, alkaline soils. Hardly any trees grow there so it's hard to get wood. Cold places where the organic material doesn't wear out quickly. Where drainage is naturally good. There was a professor from Missouri who wrote that such places had healthier people because they retained more minerals in their soils. He was kind of a permaculture precursor. Where people haven't destroyed the soil structure through plowing, pesticides, and synthetic fertilizers. Where there still is a healthy and active ecosystem.
In my opinion, those are the places where biochar would tend to be less helpful. I agree with you that it would still help.
Yes, I have. As I think of the Great Plains, the soil was naturally deep, rich and great. Many native grasses had very deep roots. It didn't need biochar to be added to it. Montana is probably somewhat like that. I was contrasting that to where terra preta originated in the Amazon: Hot all year long, tons of very tall trees, very wet, very thin topsoil, which held very little mineral wealth and drained poorly. Basically the opposite of Iowa. You are making my point exactly.
Exactly...that was pyrogenic carbon produced by thousands of years of prairie fires. Humans showed up and just went with the flow. My point was that adding biochar to those black soils would probably have diminishing returns.
True, though the way that deep prairie soil is being "mined" by industrial agriculture means that more organic matter and perhaps more char will be needed soon enough. The difference between the soil in my gardens and the adjacent farmer's field is striking.
Even if you're in a place which doesn't "need" biochar - due to geography, history, weather, etc - if you have extra woody material/invasive plants, making biochar takes "short-cycle" carbon and changes it to "long cycle" carbon which appears to be beneficial to our current atmosphere even if it is a drop in the bucket. Hubby or I usually make 2 trips to our local small city approximately 12 km round trip. We figured that 3 refills of my pot making biochar in our woodstove balanced the carbon we released by driving the car. The material I'm charring is cedar shavings from a friend's small sawmill, so I'm using a "waste" product.
Yes, I'm also trying to plant trees, live with a small footprint, and protect my soil. Biochar is only part of the solution.
Good point, Jay. Making the world a better place is just as important as improving the fertility of our soils in our farms and gardens.
Part of the reason I brought up this discussion is because I was sitting on the fence for years, trying to figure out if I was going to commit to making biochar and how to make biochar in my particular situation. I also wanted to hear from people who noticed a difference in their growing after adding the biochar.
Carbon sequestration is just as important a reason.
I reckon that in places where biochar might not be the bee's knees for the soil (and admittedly there are some) we can still use it for so many other things that it makes huge amounts of sense. Chuck into the compost heap. Use it as the basis of potting mix. Humanure and waterless toilets. Aggregate for plaster and mortar. Water filtration. Animal bedding. And as Doug points out, those fantastic prairie soils are all ending up in river deltas, so they need to be replenished and rebuilt.
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