happycobber wrote:
There is a lot being said of biochar currently, but I have my doubts. First, since things run in cycles, it is an opportunity to bring up an old topic and champion its use. It will be some time before the theory will be disproven.
What tells me it's not all that good is that people in the South American forests have been burning the forest to raise beef for US consumption, and then every few years they have to move to another locale. So, what happened to all those benefits of bio char.
Next question: what is available in the char that is not available in the wood, and over a longer period of time?
So, basically I can't prove anything, but, since biochar DOES rely on burning some portion of the wood, there goes some of that straight into the air instead of the soil.
Personal, but very educated and experience, biochar is pure bunk, but is soneome's great bandwagon. No offense intended.
Thekla
I am afraid I must take issue with you. First; there is a world of difference between "burning the forest" and making biochar. Piling wood into big heaps and setting fire to it may leave you with some ash and cinders and possibly some biochar by accident, mostly not. Biochar cannot burn as the material is in an enclosure with no oxygen, the heat drives out the oxygen and the rest of the volatiles which are then burned, leaving only the biochar.
Secondly, If biochar is done correctly, there is virtually no emission into the air; secondary burning takes care of that. If it is done incorrectly it is horrendously polluting. There is no excuse for doing it incorrectly, though, and I wish that whoever put that "official biochar" video on You Tube could be forced to breathe what he is putting out..it is a cameo of how NOT to make it. What is burned (the volatiles) include methane, formaldehyde, carbon monoxide and a number of other nasties that aren't normally regarded as having any usefulness in the soil.
I made several batches of biochar with dry wood scraps or cardboard last winter in my wood space heater. Just once I took the container out before it was finished and nearly choked. You learn fast when you do it in an enclosed area!. The rest of the time I gave it enough time and there were NO emissions, I made sure there was always flame under the openings in the container to burn anything that came out. It's actually a fairly restful process except for the dull roar of the escaping gasses..you can actually watch them streaming out and catching fire. Anyway.
I ran a small experiment this summer with biochar in two raised beds and none in the others. The same amount of water given to all the beds left the ones in the usual beds on the verge of stress all the time whereas the biochar bed plants seemed very comfortable and never showed any sign of wilting from the heat/dryness. The tomato & lettuce plants in the biochar beds sailed through a hailstorm that decimated the tomatoes and lettuce in the other beds. (and they were alternating beds so it wasn't some sort of freak wind pattern that missed them).
I have no idea about the food values of the plants one vs the other but I can tell you I am going to make a lot more biochar this winter to put on the beds next summer. Hauling water is not my fave summertime activity, esp since I found out there are leeches if the river. yuck)
Also, I did (and will) condition the biochar for several days before it was used. Fresh raw biochar will pull nutrients out of the ground at first, just as straw or any other carbon material will do when placed in soil. Thus you need to let it sit for several months or condition it.
The strength of biochar isn't that it gives nutrients to the soil as it is almost pure carbon. What it does do is provide places for the miniscule beasties of the soil, bacteria and so forth, with places to live and shelter, so they don't get washed away with rain etc and can do their part in making your soil healthy and vibrant. Apparently it also helps with holding a degree of moisture in the soil..(for some reason I hadn't expected that!) And, of course,it sequesters carbon indefinitely.
It's always unfortunate when something is touted as the answer to all problems as that is never true. However, it certainly doesn't mean that that same something is "bunk" and useless for anything. Several studies have been done in all sorts of countries and it seems fairly well established that biochar certainly has a positive role to play - with the provisos that it is properly made and conditioned and used appropriately.
There is some question about the usefullness in temperate climates vs the warmer ones and those studies are ongoing. My small trial convinced me that it has uses in my Zone 3 climate in my garden. I think it likely that people who use it and ALSO use chemical fertilizers will be disappointed as it doesn't matter how hospitable you make the soil look..if you poison it with chemicals then nothing can live in it anyway.