Amazon Black Soil - Terra Preta

Discussion in 'Gardening Other' started by Daniel W, Apr 5, 2024.

  1. Daniel W

    Daniel W Hardy Maple

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    I was thinking about this on this chilly morning.

    Where I grew up on a family farm in NorthEast Missouri, the soil was badly degraded. A few generations of plowing and disking, with wind and rain and with growing crops, resulted in the best loam soils blowing and washing away. By the time my family had the farm, there were deep gullies. The soil was a light brown, clay and sand. Crops still grew, but not well. They required fertilizers for every crop. The state department of conservation, with land owner permission, constructed earthen dams across the deepest gullies, allowing them to fill with water. Two were twenty feet deep. We stocked them with fish. The state also provided bundles of tree saplings, for erosion control. Over a decade, we planted more than a thousand trees. Those parts of the farm were useless for farming, but made for some beneficial re-wilding through hard work and time.

    In the Amazonian rain forests, the natural soil layer is thin and poor quality, leached of nutrients and spongy structure by the endless rains. It doesn't do well for farming and gardens. But it's been discovered that the Amazonian people farmed some of those areas for thousands of years, depositing layer upon layer of organic material, ash, charred material from fires, food waste, bones, manure, and pottery chards. Those deep deposits built up a deeply rich, productive, nutritious black soil - terra preta.

    https://www.science.org/content/article/ancient-amazonians-created-mysterious-dark-earth-purpose

    https://earthundaunted.com/terra-preta-how-charred-wood-created-millennia-of-soil-fertility/

    Compared to surrounding soil, terra preta is less acidic (by a pH point), and much richer in minerals. From the wikipedia article,

    "Terra preta is characterized by the presence of low-temperature charcoal residues in high concentrations;[2] of high quantities of tiny pottery shards; of organic matter such as plant residues, animal feces, fish and animal bones, and other material; and of nutrients such as nitrogen, phosphorus, calcium, zinc and manganese.[6] Fertile soils such as terra preta show high levels of microorganic activities and other specific characteristics within particular ecosystems."

    https://en.wikipedia.org/wiki/Terra_preta

    I think it's interesting reading.

    For some years now, it's been possible to purchase bags of biochar - partially burned wood, finely ground - to add to gardens. It's expensive. I have bought a couple of bags and added to my raised beds. I think it's beneficial to add back, whatever we have removed through gardening. Most of us are active composters, which I think is our best of all soil building tradition. I make use of what I have. Pacific Northwest soils are usually depleted of calcium, due to the rains. So I add about a pound of crushed eggshells to each bed, annually. I add a dusting of wood ashes - careful not to overdo it. During winter, kitchen scraps get buried. Of course any garden with hens will have chicken manure. That gets composted. We go through about a pound of coffee grounds in a week. That's 52 pounds a year, so over the past decade, 520 pounds. And I add bone meal.

    When I have to dig in other parts of the yard, it's a very clear difference. The enriched beds have spongy, black soil. It's easy to dig, and there are countless earthworms. In comparison, the unenriched areas are hard as brick in summer, and clay like in winter. There aren't many worms. Grass grows there, but not lush. Some weeds like it.

    One last thing. What is in our soil, goes into our plants, then our food. Foods grown today, in modern fertilized but nutrient-depleted soils, are MUCH less nutritious than they were 70 years ago.

    https://www.scientificamerican.com/article/soil-depletion-and-nutrition-loss/


    From the above article - " They studied U.S. Department of Agriculture nutritional data from both 1950 and 1999 for 43 different vegetables and fruits, finding “reliable declines” in the amount of protein, calcium, phosphorus, iron, riboflavin (vitamin B2) and vitamin C over the past half century" . Also, between "1975 to 1997 found that average calcium levels in 12 fresh vegetables dropped 27 percent; iron levels 37 percent; vitamin A levels 21 percent, and vitamin C levels 30 percent. A similar study of British nutrient data from 1930 to 1980, published in the British Food Journal,found that in 20 vegetables the average calcium content had declined 19 percent; iron 22 percent; and potassium 14 percent. Yet another study concluded that one would have to eat eight oranges today to derive the same amount of Vitamin A as our grandparents would have gotten from one."

    Probably flavor, too.

    I hope this is interesting. I think the key point is that continuously building our soil quality is a good thing for gardens and for us.
     
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  2. Sjoerd

    Sjoerd Mighty Oak

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    Mate this IS interesting; or more importantly— important. Soil is everything. A garden succeeds or fails on its soil. It is the basis. This is why I am so totally in agreement with you. I think I spend more thinking and working on soil than anything else in the gardening season rest phases. It is so important to replenish one’s soil and keep the structure optimal.

    Of course it is important for the hobby gardener, but also for the wider country and world picture.

    Thank you for your posting today.
     
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  3. Pacnorwest

    Pacnorwest Hardy Maple

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    Daniel Great post and interesting technical soil amendments can be extremely practical for the average gardener.

    Example an experiment in my old burn pile. I never burn anymore I have left ash and the charred area with piled yard debris over the top now for over 8 years . Debris all breaks down on its own. The last few years the burn pile Island in the middle of the posture has grown many different plants from seed, branches and other waste from gardening clean up. Now it sports ‘Super black’ soil on its own devices. Basically making its own bio-garden every year. Never needs water or attention. Every season flowers pop up , shrubs, small trees even during the heat of extreme summers never needs water. Compliments of the gopher and moles have tilled the soil under and near by important addition of oxygen to the island the size of 20’x20’.

    Nature can revive land soil and plants on its own. Mere proof from an old burn pile that has turned into a garden island all on it’s own simply by letting nature care for its own environment with no intervention other than adding on more waste from the gardener, rains and heat from the seasons and nature does the rest.
     
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  4. Daniel W

    Daniel W Hardy Maple

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    Thanks Sjoerd and Pac. Obviously, I think about these things quite a bit too.

    I think we have to be aware of what we are doing. Since we've bee depleting soils for a very long time, and it shows in our vegetable and fruit nutrition, I think it's a good thing to put back into the soil as much as we can. Not harmful stuff, of course. For example, if burn piles contain wood from old preserved fencing or other preserved wood, they may add arsenic t our soil and diet. If wood that grew on roadsides, before lead was removed from gasoline, is burned, maybe it will add lead to the soil. I don't know.

    One of the articles said that Amazonian earthworms can ingest particles of charcoal and grind them finer. I saw some big night-crawlers yesterday. Maybe they do that too?
     
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  5. Pacnorwest

    Pacnorwest Hardy Maple

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    You have a good gardeners heart and preserving our soil is something most take for granted, taking care not to damage the soil with poisons in materials used for gardens.
    We have huge night-crawlers in the garden areas not the pastures. I think it’s because I trucked in tons of mushroom compost/topsoil to build up all the garden beds by 8-10 inches. Lots of healthy worms means healthy soils.
    What are those worms called that eat at plant roots ? I can’t remember do you?
     
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  6. Daniel W

    Daniel W Hardy Maple

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    Could it be nematodes? Not really a worm, but look kind of like microscopic worms.

    Or symphyllans? Also not a worm, but a tiny soil pest in western OR and WA. I've read about them, and they can be highly destructive. They feed on plant roots.

    https://ippc2.orst.edu/mint/symphfact.pdf

    Or the jumping worms? They have hippity hop hopped to Oregon too.

    https://today.oregonstate.edu/news/invasive-jumping-worms-leap-oregon
     
  7. Pacnorwest

    Pacnorwest Hardy Maple

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    I have read of the destructive nematodes eating rose roots in warmer climates. And those jumping worms YIKES…

    Nematodes….Yes that’s it …Thank you :). I had a brain fart…. It seems to be another thing haunting my aging brain.
    I have used beneficial nematodes as a pesticide in the gardens for many years.
    Have you ? Purchased online and they come in a dried sealed medium. They are Live and must Use them right away. Measure out in a hose end sprayer and sprayed the gardens and yard. I never knew if they did any good or not. But I digress….

    What I wanted to do was to introduce these 2 quick articles on nematodes that have been used by their color changes to identify toxins in buildings . I read about a few years ago .
    https://drtomsclassroom.com/what-color-is-your-nematode/

    Another article on how they are used to monitor indoor impurities.
    https://www.sciencedaily.com/releases/2023/02/230203105341.htm

    Health aid for people who have breathing conditions or allergies. I haven’t seen any of these devices available to the public yet . I read it was also designed for home use .

    Hopefully it was interesting enough to share .
     

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