sterilizing soil

Discussion in 'Gardening & Plant Propagation' started by wormlady, May 4, 2005.

  1. wormlady

    wormlady Well-Known Member Supporter

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    I read somewhere of someone who poured boiling water on her soil ( in containers) to sterilize it.
    Does anyone know if this would make it possible to plant tomatoes in the same pots they were planted in last year?
    I know you are not supposed to plant tomatoes in the same area from year to year. Just wondering if the boiling water would take care of the problem.
     
  2. okiemom

    okiemom Well-Known Member

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    you can sterilize soil in your oven. Can kind of stink up the house though. Sterilize pots by bleach water. you can also sterilize soil by placing it under a black plastic tarp for several months. I am not sure boiling water would be a true sterilization. you might use that soil on a different species and rotate soils like you would in a garden plot.

    Is this just for prevention or do you have a current disease problem?
     

  3. Sedition

    Sedition Well-Known Member

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    Sterilizing soil is not the best idea, although I do use it to control pathogens. It also is not practical to sterilize garden soil, although potting soil for a single tomato planter (about 20 gallons I figure) is doable.

    The downside to sterilizing soil is that you kill the good microfungi, microflora and microfauna. Your soil is a living ecosystem. Most of what is in your soil is good for your plants. Although most people understand that legumes need nitrogen fixing bacteria, few people understand that all plants have some level of symbiotic relationship with microfungi. These fungi break down organic matter in the soil, including dead bacteria, and release the nutrients in an elemental form to the plant. Without these, you might as well plant in nothing but vermiculite – as doing this would be better for your plants.

    If you need to sterilize a planter pot, boiling water will work. You need a lot of water! The goal is to get the temperature of the soil up to 212 degrees for 20 minutes. In a laboratory setting, I’d sterilize soil for 60 minutes at 240 degrees / 11 pounds of pressure in an autoclave (same thing as a pressure canner, only bigger). 212 degrees for 30 seconds will kill growing weeds. 212 degrees for about 5 to 10 minutes will kill seeds or living bacteria and fungi, but 20 minutes is needed to kill spores.

    All of this means that you’ll need a hundred or so gallons of boiling water, and you’ll want to pour the soil into it. An oven set to 350 is a better idea, but it stinks (I’ve done it).

    The absolute best solution is to simply improve your soil. It is too late for the 2005 summer, but this fall till or dig in about a wheelbarrel full of chicken manure into each 4 square foot section that you grow tomatoes in. This “hot cured compost” will add a substantial amount of organic matter to that spot, and it will encourage the beneficial microorganisms that that plants need to stay healthy and fight the bad fungi and viruses.
     
  4. wy_white_wolf

    wy_white_wolf Just howling at the moon

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    By the Square Foot Garden book, Tomatoes do very well planted in the same spot year after year.
     
  5. wormlady

    wormlady Well-Known Member Supporter

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    Thanks for all the good advice!
    I had decided not to oven sterilize cuz of the smell. DH has a real sensitive nose and I don't want to do that to him.
    I had thought about the killing of the good stuff in the soil, but was hoping maybe the benefits of getting rid of the bad stuff would outweigh that.

    I didn't realize it would take so much water though.

    I think what I will do is replace some of the soil with compost, add lots of worm castings and plant in the same pots with reckless abandon!