The use of oyster shells in soil mixes?

Discussion in 'Soils, Fertilizers and Composting' started by Karalyn, Nov 19, 2007.

  1. Karalyn

    Karalyn Active Member

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    Hi,
    I have read that oyster shells were good to put in soil. So I have purchased a few times the large bag of oyster shell, which I am to understand that this is the chicken grit that is actually what is used to add to soil mixes.

    I have added oyster shells to my potting mix and garden beds to help the clay soil drain better and easier to pull a weed out.

    I haven't found a problem with it, but have wondered if this is the "chicken grit" that the gardener was using for his soil as an additive.
    Also, I read in the UCDAVIS soil mix that someone linked to in Creating Soil, I think...use oyster shells to their soil mixes. So I guess I'm on the right path, but wondered about the salt factor that is on or in the oyster shell as helping or can cause a problem?
     
  2. Poetry to Burn

    Poetry to Burn Active Member

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    I bet processing the shells would remove most of the salt? Do you know if the shells had much effect on pH?
     
  3. Karalyn

    Karalyn Active Member

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    I haven't tested for PH, just know that plants still grow with it in the mix and I have even grown clematis seed with the shell as the top layer, I chose that because what was suggested was aquarium manufactured tiny pebbles and I feel that they are too expensive when there has got be other stuff cheaper I could use.

    I also have used perlite on top of clematis seeds.
     
  4. obejunction

    obejunction Member

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    OYSTER SHELLS IN HYDROPONICS
    Does anyone know if oyster shells will work well in a flood and drain system?
    My interests are in finding free lite weight media for my AQUAPONICS SYSTEM.
    I'm also thinking walnut shell might be good.
    Any suggestions good people?
    Thanks
    John
     
  5. Karalyn

    Karalyn Active Member

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    I would think the oyster shells should do well. Depends on how big is your drain system going to be. Maybe the light weight aquarium pebbles might be better. I'm not sure about walnut shell, I guess it depends on whether you are putting it into a tank that will be full of water, such as when fish keepers filter their water via a tank full of water and small gravel, etc. and planted with water plants. The purpose is two fold, plants grow in it and the plants filter the water for clean water for fish. Size of tank needed will help in your decision making as well as rinsing ability and preventing clogging of too porous of a media.

    P.S. I don't know about the breaking down of walnut shells and how that would affect your purpose. Is it the draining of moisture needed or is it moisture that you want to keep. That is where I don't know how walnut shells will help or hinder.
    Another thought is volcanic rock, although it can be heavy, the more porous it is, the lighter it weighs, until it is clogged by debris.
     
  6. obejunction

    obejunction Member

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    Thanks for the reply.
    My concern about the breaking down of walnut shells is if it breaks down into some slushy material that'll need to be removed in time or will it break down clean and only need to be toped up occasionally?
    It sound however that your only guessing. Who will know for sure???
    Thanks again
    John
     
    Last edited: Oct 8, 2009
  7. thanrose

    thanrose Active Member 10 Years

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    Your biggest concern with the filter media should be what it does to the water.

    If you use walnut shells, they have the variable surface that's desired for biological media, but they will leach tannins into the system's available water.

    Oyster shells will leach calcium into the water.

    Either one would effect your pH.

    For both of these it's a matter of degree. Some bags of crushed shells of either will have less readily dissolved parts. At some point, they'll be stable. You could try suspending a bag of either in your toilet tank or in a sizable stream to monitor for a couple of days.

    A small amount of oyster shell or walnut shell could be put into an aquarium with little or no effect. Using either for significant filter media in an aqua system of any size would mean frequent water testing and possibly necessitate a draw-down and replacement of media and water.

    Have you seen the plastic pellets used for aquarium filtration? I'd try any food grade inert plastic chopped to bits for filter media before I'd use organic shells that I know will add something to the water.
     
  8. Karalyn

    Karalyn Active Member

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    I guess that is my question, I think broken up walnut shells are fine, if the purpose is to put them in a pit like or sunken flower bed, because their breaking down process just enhances the flower bed, such as composting. English shells vs the black walnut tree shells are different too.
    We've had discussions on the effect of walnut trees affecting things growing is places where they use to grow. I have an English walnut tree and no problem, growing up in California with neighbor's that had black walnut trees, never posed a problem either. So basically, it is your experiment, and that will be an interesting report when all is said and done. Should be fun to read about. :-)
     

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