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Secret of Terra Preta Soil Discovered? — 4 Comments

  1. Random bits and pieces of biochar info from various sources (things to think about/look into more):

    – Note the large amount of broken pottery in terra preta soil. There’s way more than just a few pieces of broken pottery. Large amounts were obviously added for a reason. One possibility is pottery is adsorbent — it takes contaminants out of the soil.
    – Consider adding rock dusts for additional minerals.
    – Add nitrogen-fixing bacterial inocculants and mychorrizal inocculants — possibly gleaned from good soil under old growth trees (IMOs).

  2. By the way, there’s plenty of other positive information supporting biochar. For instance, there’s a world class research center 15 minutes down the road that uses it in all of their potting mix and probably all of their plants. They could use anything they want and so this speaks volumes. They make a slow compost where all of the materials are aged a year or so. I used to have their recipe. It’s something close to this:
    – aged rice hulls
    – rice hull ash (biochar)
    – local sandy/clayey soil
    – aged cow manure
    – last time they were sprinkling in some lime on the final step

    We visited a nursery east of here that uses the same basic recipe. They age the mixture an additional year to allow time for the microorganisms to populate the mix.

  3. I question a lot of biochar claims. I read one peer review study showing that biochar buried in a forest broke down over a 10 to 30 year period depending on the type of pyrolysis, not thousands.

    I’d rather see people make quality compost with high water holding capability with the organic material instead of burning off the volatile compounds and exposing the less volatile ones that some soils may be deficient in.

    The only scientific research I’ve seen where biochar alone improved growth rather than reduced it (most peer review studies) was for Avocado trees and other plants planted in saline soils. Whereby as saline ground water rises, the biochar then acted like a carbon filter.

    For me, innoculating biochar is akin to liquid fertilizing using an absorbant medium as biochar holds water ~50% by volume. To me it has some parallels to the Mittleider method, which may explain some exceptional results. Plants love liquid fertilizer, they love anything that saves their roots and the symbiotic microbes in the soil from having to do all the work mining those minerals. And since soil moisture of about 40% is ideal for most plants biochar may actually help some with hydrophobic soils, but then so would compost.

    I’m also skeptical that microbes populate biochar cells. I read a biochar thesis that showed electron microscope images where microbes hadn’t populate the pores of biochar, and rather stuck to the surface, and that clay particles in soil tended to block the pores. Many clays actually have antimicrobial properties too, and even kill drug resistance superbugs.

    From my research, if you really want to sequester carbon for long periods it needs to be prevented from oxidizing. Some plant and microbial exudates do this by surrounding the carbon with a membrane, and some fungi also sequester and store carbon inside microaggregates where other microbes can’t get to it. However the best way I’ve seen to build long lasting soil organic carbon is to send it deep into the soil horizon and to do that you need perennials with long thin hair-like roots capable of penetrating small crevices. Over the seasons these roots grow and die and sequester organic carbon.

    • Yes, it’s good to be skeptical. That’s why I wrote the title as a question. When I heard the people in these videos all talking about permanent fertility like terra preta soil, it really piqued my attention. Let’s hope it’s true. One thing is for sure — terra preta soils were man-made and they’re still super fertile. Someday soon we may understand how it works so it can be replicated.

      What are you favorite deep rooted soil building plants? Comfrey?

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