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Put too much dolomite in my soil less mix

Discussion in 'Organic Growing' started by dabbish, Feb 20, 2011.

  1. #1 dabbish, Feb 20, 2011
    Last edited by a moderator: Feb 20, 2011
    I mistakenly put 5 times as much dolomite in my LC's soil less mix (and I wasn't even stoned at the time). What I know about dolomite is that it's there to balance the PH right? So is it possible to put too much? Can I still use it or should I use that mix next time I mix another batch?

  2. ...you are correct, lime is used to prevent your soil from becoming too acidic....however, your soil does needs to be slightly acidic. Lime has a neutral pH, meaning it will only raise your pH to 7 at the worse case scenario. Dolomite lime also provides cal and mag.

    ...can you dilute your mix with more soil?

  3. Just how much was your 5x too much? Per gal or CuFt.

    I use 1 cup/CuFt of LC's mix.

  4. Thanks for your replies guys.

    @trichome fiend

    Yes I can dilute it with more soil. But I rather not.


    I used 5 cups per cubic foot.
  5. Dolomite contains a lot of available Mg....you could see some issues related to that.
  6. #6 Possuum, Feb 21, 2011
    Last edited by a moderator: Feb 21, 2011

    You should probably ensure that you have a minimum 40% of soil organic matter in your base soil mix (pre-nutrient). This is most easily accomplished by the addition of quality EWC and/or a quality finished compost. This will boost the reserve capacity of your soil cation exchange capacity and may help overcome the basic (alkaline) properties of lime to increase soil pH.

    The biggest challenge to overcome when overliming is the chemical reaction that takes place in the soil and base (alkaline) buffer that use of lime produces. For the most part and if left untreated an overlimed soil should probably be considered "permanent" in the sense of a 120 day grow cycle. If you recycle your soil eventually - perhaps - the effect of overliming can be overcome. But one would have to take direct action to alter the soil chemistry to overcome the use of too much lime.

    Another way to help counter overliming is through the use of acid forming fertilizers, typically N, which when converted from ammonium to nitrate will result in acid being released. There are literally 10's of thousands of documents in the .edu agricultural domains that discuss lime's chemical properties, what it does to the soil, its buffering capacity, etc. etc. Lime, and there are many different forms of lime, has been used for more than a couple of hundred documented years of crop agriculture.

    Following is but one sample quote. Like I mentioned there are 10's of thousands of documents covering a vast array of lime quality and lime usage topics. Be real careful with lime and container gardening. A little bit goes a very long way in a very short time. Without a valid soil pH test measuring soil buffering characteristics it is nothing more than urban myth that every soil mix should have some lime added. Just ain't true just because that's the way Grandpa always did it. One had to know what one is starting with at the soil level before ever using lime in the quantities you've used it. Generally speaking most packaged soils are at or near neutral pH, add plenty of soil organic matter, use alternate sources to obtain your Ca and Mg and leave the lime alone.

    FWIW this is MHO.

    "Do NOT over-lime! Lime adjusts soil chemistry, it is not a fertilizer. A little too much can raise pH to undesirable levels and keep it there, causing serious management problems. Make certain you know how much lime is needed, then apply it over a number of seasons until your soil is back in balance."

    Soil pH, Fertilizers, and Lime
  7. #7 dabbish, Feb 21, 2011
    Last edited by a moderator: Feb 21, 2011

    Thanks for posting that article. I am using LC's soil less mix (50% peat moss, 30% perlite and 20% worm castings).

    What is your take on the mix I made? Do you think I can dilute it with a few other batches?

    By 40% organic matter, would you then be referring to e.g worm castings?
  8. I think you should mix this batch in with a new batch

    It's definatley still usable soil, it just needs to be cut with some fresh soil first


  9. Yes, of course you can dilute it with a few other batches.

    Just how much did you make? How many CuFt?

    I mix mine in 2CuFt batches, because that's what my wheelbarrow holds, but usually make 4-12CuFt, or as long as my back holds out.:cry:Bolt Those 30 gal trash cans from HD hold 4CuFt nicely.

    Keep Your EWC to 20%. LOL 40% would turn your mix into concrete. I also found out the hard way about using BOTH mushroom compost and EWC in the same mix. Way too heavy and had to parcel it out into other batches. And there was a ton of perlite added to no avail.

  10. I made 5 cubic feet. But no worries, I will just dilute it. Thanks for all your replies guys.
  11. Dolomite lime takes 7 - 9 months to completely breakdown which explains why it's such a poor liming agent.

    You have absolutely nothing to worry about in a 5 - 7 month container grow.


  12. ....awe, there's different kinds of lime....rapid release dolomite lime is active near immediately.
  13. trichome fiend

    I heard that - I guess you mean really complicated stuff like calcitic lime, calcium carbonate, calcium hydroxide, calcium magnesium carbonate and such? That really icky stuff you have to learn in Botany 101?

    At any rate if you have some jamoke telling you that 'dolomite lime' can or is instantly available then get them a copy of Bill Wilson's book and get him to the meetings. It's the least that you can do for them.


  14. ...I smell sarcasm.
    ...actually, I'm referring to hydrated lime, aka Quick Lime....active in 2 weeks.
    ...read up >>> http://www.paulparent.com/now/dirt.html

  15. Are you saying the dolomite doesn't become available to the roots until 7-9 months? Or do you mean that after that time the dolomite is used up?
  16. I kinda thought that you were - unfortunately.

    Hydrated lime (Calcium hydroxide) is something that one should look long and hard at before considering this as a soil amendment.

    To each their own!

  17. #17 FormerLumperDaw, Feb 22, 2011
    Last edited by a moderator: Feb 22, 2011

    For the sake of this discussion, the mineral that you're wanting to be available to raise the pH is Calcium, correct?

    Dolomite lime consists of Caclium (Ca) in its elemental form and Magnesium in the form of Magnesium Oxide. The molecular structure reads like this: [Ca] • [Mg(CO3)2] and crystallizes in the trigonal-rhombohedral system according to the crystal folks. An interesting group to be sure.

    With the Calcium so tightly bound with the Magnesium Oxide a great deal of microbial activity has to happen before the Ca is released to do its job which is to grab and hold the Hydrogen (H) atoms - that's the "H" in pH - Hydrogen. One atom of Ca can grab and hold onto 2 H atoms - Cation Exchange. While Hydrogen doesn't play a major role as does macro and micro nutrients, the roots of a plant exude Hydrogen as a 'rate of exchange' for the cations held in place by the humus. Magnesium, Potassium, etc. are moved into the vascular system of the plant via this process. Not all macro and micro nutrients are handled in this way as others are moved into the plant through the various fungi colonies.

    So if you feel that you need to use Ca specifically as a soil amendment you have an equally inexpensive choice - limestone.

    Limestone (depending on which region of the world it's coming from) has around 95% Calcium Carbonate - the same stuff that's all over your earthworm castings assuming that they were produced and harvested correctly. EWC = massive levels of Calcium Carbonate.

    Back to the Calcium Carbonate levels in limestone the molecular structure goes like this CaCO3 [Ca] • [C] • [O x 3] meaning that you have 1 unit of Ca, 1 unit of Carbon [C] and 3 Oxygen [O] units. Since we're trying to grow aerobic microbes the additional O component will be beneficial.

    Carbon doesn't need any explanations - the base of life on this planet. Breaking the bonds between the Ca, C and O is fairly quick.

    EDIT: When looking at a Calcium Carbonate source (limestone or oyster shell powder, etc.) you need to take 38% of the total Calcium Carbonate expression on the product to arrive at the level of elemental Calcium (Ca++) it contains.

    Just keep in mind that the contribution that Ca makes in a soil is not one of pure chemistry, per se. It's more about the exchanges between negative-charged components in the soil like humus & clay in particular and with the Cations that can move the pH in several directions.

    Something like that.

  18. #18 dabbish, Feb 22, 2011
    Last edited by a moderator: Feb 22, 2011
    Well, I am just following the recipe. I just wanna keep it simple.

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