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Post by paquebot on Sept 22, 2014 13:23:42 GMT -5
Biochar itself would be neutral since it is basically carbon. The bi-product of making it is wood ashes and they are highly alkaline. Making it in a barrel, kiln, or whatever and then transferring it to soil is fine. Making it in place via a burning pile is not as it would take years of leaching in light soils to get the pH back to something that the plants can handle. Would take twice as long in heavy soils.
Martin
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Post by Joseph Lofthouse on Sept 22, 2014 21:52:36 GMT -5
flowerweaver: It is common for me when I get a new field for there to be spots in it that are basically dead for about 3 years where the hay was dropped for the animals. I attribute it to herbicide residues. One of the fields that I used was heavily over-sprayed with weedkiller for years before I started using it. That was a tough field for the first couple of years.
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Post by steev on Sept 22, 2014 22:00:52 GMT -5
Burning in place is why "slash-and-burn" was so unproductive and rarely used by native peoples, I suppose.
I'd be far more concerned about burning PT scraps, as such, and am surprised that that hazard hasn't been mentioned.
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Post by paquebot on Sept 22, 2014 23:20:07 GMT -5
Slash and burn is most widely used in what is/was rain forest or similar. With so much rain, the trees and plants life cycle is geared to recycling almost all nutrients in a single growing season. With very rare instances, all rainfall is acidic as are the rivers and streams in many of those areas. It's not being done on alkaline soil as that will never work. Slash and burn in those places raises the pH to something that the crops can handle and use a generation of nutrients in only a few seasons. Then it must be left to regenerate for a number of years.
Martin
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Post by steev on Sept 23, 2014 1:37:28 GMT -5
Do you really want to go there, Martin? Do you really want to scale his trash barrel up to industrial scale? Do you really want to get all pontifical about a trash-barrel full of ashes? I spread ashes on my land whenever I have them; doesn't hurt a damned thing. My tomatoes love the soluble calcium and phosphate.
I think very few here, if any, are growing in tropical rain forests, where what hits the ground is so rapidly taken into the canopy.
While there are certainly soils that are alkaline, plants can benefit greatly from readily available nutrients, such as are available in ash.
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Post by oxbowfarm on Sept 23, 2014 14:15:02 GMT -5
Semi-nomadic agriculture involving slash and burn was not limited to the rainforest. It was the basic methodology for all the corn growing cultures of North America east of the dry line. If you consider this area was covered in a continuous forest and these cultures had basically no livestock or metal tools, it makes a lot of sense. Fire is the best tool for clearing forested land absent metal cutting tools. Girdling the trees, planting underneath them and then burning them off once a few years later when they had dried enough to burn was the easiest way to make a cornfield. Then you use that field continuously till the fertility drops below a certain economic threshold. Then the whole village picks up and moves to a new site and the old site lays fallow and regains fertility. Slash and burn is actually a fairly sustainable agricultural system if population density doesn't get too high.
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Post by steev on Sept 23, 2014 18:54:34 GMT -5
No small part of why Native Americans didn't get what the Europeans were on about with their "This is MY plot of land, and I'm going to stay right here and farm it forever. You have to keep out; I don't care if it was your Summer camp-site or your hunting-trail went through here since ever; it's mine because I paid money for it!"
In California, the indigenous folk commonly used fire to clear the undergrowth in forests; keeping things less "brushy" made it easier to gather acorns and horse-chestnuts, both staple storeable foods for them; frequent planned burns also avoided the sort of disastrous uncontrolled wildfires we're seeing so often, these days.
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Post by paquebot on Sept 23, 2014 22:46:01 GMT -5
Do you really want to go there, Martin? Do you really want to scale his trash barrel up to industrial scale? Do you really want to get all pontifical about a trash-barrel full of ashes? quote] I have no idea what you are talking about! I responded to Minnie's question and that would have been basically a brush pile! Martin |
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Post by paquebot on Sept 23, 2014 22:53:48 GMT -5
Semi-nomadic agriculture involving slash and burn was not limited to the rainforest. It was the basic methodology for all the corn growing cultures of North America east of the dry line. If you consider this area was covered in a continuous forest and these cultures had basically no livestock or metal tools, it makes a lot of sense. Fire is the best tool for clearing forested land absent metal cutting tools. Girdling the trees, planting underneath them and then burning them off once a few years later when they had dried enough to burn was the easiest way to make a cornfield. Then you use that field continuously till the fertility drops below a certain economic threshold. Then the whole village picks up and moves to a new site and the old site lays fallow and regains fertility. Slash and burn is actually a fairly sustainable agricultural system if population density doesn't get too high. Didn't say that it was limited to the rain forest parts of the world. When done by the largest population doing it, it was and still is in the Amazonia area. Where there was always more forest to slash and burn, no problem to just keep using up what was there and move one. When that was no longer possible, the population starved. Happened throughout Amazonia and happened to the Mayan populations. Martin |
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Post by steev on Sept 24, 2014 0:18:26 GMT -5
And yet you came in so well after mikew's mention of his burn-barrel, and then referenced Amazonian rain-forest nutrient recycling, paquebot. As for the notion of Amazonian or Mayan populations exceeding the capacity of their environments agriculturaly, that is bat-crap. To the extent that those ecosystems have/are being over-exploited, it is due to thoroughly non-indigenous extractive slash-and-trash agricultural practices; soybeans for export, for instance. I don't think Mayan or Amazonian Indians are growing soy for export. That seems more "Big-Ag" to me.
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Post by Joseph Lofthouse on Sept 24, 2014 1:12:24 GMT -5
The story is told that the Indians in this area (a valley in the Great Basin Desert) used to burn the valley from time to time because fire kills sagebrush and replaces it with grasslands which created better grazing habitat for the animals that they hunted.
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Post by reed on Sept 24, 2014 4:33:34 GMT -5
I know the Amazon burns now, you can see it on the NOAA and NASA satellite pictures but how in the old days did you start a fire of any size in a place that got 300 plus inches of rain per year?
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Post by littleminnie on Sept 24, 2014 9:11:38 GMT -5
Hey I wasn't talking about burning on the ground but making terra preta in a covered hole like the original method of slow burn buried in the ground.
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Post by paquebot on Sept 24, 2014 11:54:39 GMT -5
Hey I wasn't talking about burning on the ground but making terra preta in a covered hole like the original method of slow burn buried in the ground. That you can do since you are making a kiln. No difference than if it were an aboveground dome or a pit. Either way, you're not going to be able to plant directly into it but rather spread it throughout the garden. "In situ" would mean that where it's made is where it is going to stay and that ain't feasible without many years of weather, microbial, and other actions to allow plants to grow in it. Although slash and burn would be off-topic, it is not a method which produces biochar. It is still practiced throughout the rain forest areas of the world but primarily as a one-season subsistence thing. There's generally not enough nutrients left to support a second crop. en.wikipedia.org/wiki/Slash-and-burn_agriculture Martin |
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Post by mnjrutherford on Oct 6, 2014 16:51:30 GMT -5
Little Minnie, we have a sort of terra preta pit that we started about 5 years ago. You would not plant "in situ" for what we are doing. Our set up is 2 side by side pits about 3' by 5' each. They are about 18" deep with the center being deeper than sides and an 18" drain hole for water to run down and out from. There are also a couple of pipes installed that allow air to be drawn in to maintain the slow burn. We "load & burn" one pit for a year, then it is allowed to "cure" for a year. After curing period all the material is removed and spread wherever we want. The emptied pit is now ready to load and burn again. It certainly isn't anything like the terra preta pits that are so famous, but this is where we put ALL of our organic trash including dog poo and animal carcasses (possums, raccoons, whatever dies that won't be eaten). When there is a lot of "meat", we cover it with green stuff and increase the temperature a bit to get it converted a bit more quickly. We don't actually cover the pits, but the birds will check it out for tidbits and what not. All in all, it works pretty well and really keeps out out-going trash to a minimum. You might need to know; however, that where your soil is alkaline, ours is quite acid. I don't know how much of a difference that make. I hope you find this useful!  |
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