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Re: LOW-TECH, HIGH-QUALITY ON-FARM COMPOST
Hi Joel -
Please read some of the published work about how humic acid is produced.
I think we all agree that humic acids are very long-term carbon compounds. Their half life is on the order of several hundred years. There are several very good books on the subject of humic acid production. Those books very clearly show that SOME humic acids are produced aerobically, SOME are produced in minimal oxygen conditions, and SOME are produced in low oxygen conditions.
For anyone to claim that high molecular weight compounds are only produced in anaerobic conditions is silly. Any scientist should be able to see through that claim in a second.
Good compost has good aggregate structure, and the insides of aggregates can be anaerobic. As shown by the pioneering work of Sexstone and Tiedje at Michigan State University quite some number of years ago, and by quite a number of other people since the time they published that work, the insides of such aggregates can have very low oxygen concentrations, as low as 1 or 2 ppm, or less.
Thus, good aerobic compost has anaerobic microsites. BUT, as the anaerobic metabolites such as ammonia, hydrogen sulfide, acetic acid, putrescine, etc diffuse and volatilize out of the aggregates, they reach aerobic zones, where the plant toxic materials are converted to aerobic products. When these anaerobic microsites are broken open, aerobic organisms re-colonize. It is important for the diversity of foods in a good compost that BOTH aerobic and anaerobic organic material is present. Diversity is the key.
In well-aggregated composts, N, S, P, etc, are not lost because the anaerobically produced materials are captured by the aerobic organisms before those gases leave the pile. Look at the work by Malcolm Beck, for example.
In completely anaerobic material, fertility will be lost. N will be lost as the gas, ammonia. S will be lost as the gas, hydrogen sulfide. Both can easily be identified by the human nose.
If for no other reason, you can't allow your compost, compost tea, or soil to go anaerobic, because you lose the nutrients you are trying to conserve. You lose the nutrients that will result in good plant production.
The maximum production of "soil glue" occurs in aerobic conditions. Note the recent work on glomalin from the researchers at the USDA. These materials are produced by mycorrhizal fungi. Mycorrhizal fungi are STRICT aerobes. They cannot tolerate anaerobic conditions.
Check the work of Dick Wiebe at Univ of Georgia. Spartina is mycorrhizal when it grows outside the riparian zone, but is not colonized when it's roots are in anaerobic mud. when your soil goes anaerobic, the mycorrhizal fungi are lost. And thus we lose what the USDA is terming the most important binding material in the soil. Do you think that is not high molecular weight material? According to the USDA researchers, it is.
The people at the the University of Vermont who wrote those factsheets perhaps need to rely less on a single opinion. Check things out before sending things like that out.
When we are working on the cutting edge of technology and science, and there is no scientific literature on a topic, we are faced with a different situation. But there is quite a scientific literature on production of high molecular weight materials in soil. Humic acid production has been reasonably well researched, although there is quite a bit more we would like to know. To maximize the production of humic and fulvic acids, and other complex compounds, we want a mix of aerobic, intermediate aerobic - anaerobic, and true anaerobic conditions.
In 24 hour compost tea, we do not want that mix of conditions, because it is in anaerobic conditions that some quite toxic materials can be produced. In anaerobic teas, you must allow a significant period of time for the truly toxic anaerobic by-products to be consumed in aerobic conditions before using the tea.
That's why anaerobic compost teas have such long brewing times. They require two to three weeks before they can be used, because if you go anaerobic, and have Clostridium botulinum grow and produce toxin in the brew, you have to allow time to let that toxin decompose before you apply that tea.
There is a massive difference in the metabolic products produced in aerobic versus anaerobic teas, I'll stand side-by-side with Wil Brinton in saying that.
BUT, the reason I don't recommend anaerobic tea is for the reason that many anaerobic by-products are deadly toxins. If you don't understand what you are doing, brewing an anaerobic tea can be really bad news.
President, Soil Foodweb Inc.
SFI Corvallis, OR
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