Soil test results interpretation - help!

Discussion in 'Growing Organic Marijuana' started by underground-botanic, May 17, 2023.

  1. Hey dear friends,

    I have my first batch of (potential) no-till mix ready and sent a sample to the local lab after 4 weeks of cooking. The recipe is - like most of them - inspired by coot and adapted to use what is available to me locally (i'm in the EU).

    Here is the breakdown:
    Base soil = Peat moss 40% + 20% composted oak bark + 10% EWC/ Biochar mix + 30% pumice
    Amendment per cu.ft
    - 1/2 cup kelp meal
    - 1/2 cup neem cake meal
    - 1/2 cup alfalfa pellets
    - 1/2 cup chicken shit pellets (4-4-4)
    Minerals per cu.ft
    - 1 cup mix of basalt and dolomite (I have 25 kg of Cuxin DCM i use for my garden. It's 11% MgO and 32% CaO)
    - 1 cup diabase
    - 1 cup bentonite
    - 1 cup gypsum

    I have made enough soil for a full 10 gal container.

    My lab doesn't offer testing for potting mix specifically but told me their test for compost is also adapted. The problem is there is no interpretation of the results (I mean yes but for using it as a compost) and as I'm not an soil scientist, it is difficult for me to judge and compare it with tests from the USA/ Canada, with other units and methods probably also...

    My feeling is the mix is high in sodium.. Also the Ca and Mg seems to be high and it makes sense as the ph is 6.96. Ca:Mg ratio is 3.5 but my tap water contains a lots of Ca and almost no Mg so it should balance out with waterings.
    The C:N ratio of 31:1 is also very high, probably from the composted bark.

    I have estimated the CEC and base saturations by converting the FM results from g/L to meq/ 100g:
    CEC ~ 40
    Ca 62 %
    Mg 17%
    K 5%
    Na 11% (!!)
    other bases 5%

    Any help for the interpretation of the results is welcome!!

    ps: TM means dry matter and FM is fresh matter or as received.

    Attached Files:

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  2. Wish I could be more help, but I can kind of address the sodium thing. Salt is not bad for plants, but obviously too much is. The good thing about salt is that it is very easily washed out of soil. A single heavy rainfall will remove the vast majority of excess salt, or if you're in pots a single good rinse.
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  3. Wondering if some of the big brains with lotsa experience could weigh in here - @waktoo, @TimJ, @ElRanchoDeluxe, or @Organic sinse - any of you dudes think you could give OP a hand here? This particular question is out of my league
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  4. I wanted to refresh my memory and do a little homework on this one but it’s too much. If the OP had the soil test in English and did the conversions it might help some.
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  5. Oh geez. Now I see where he listed some of it and it looks good to me. I’m thinking he mixed up everything and then immediately sent it off to the lab and that’s why the C:N is 31:1 …,.almost perfect for composting. Kinda makes me wonder what if any effect this would have on the test itself?
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  6. I couldn't be of much help with it either for the same reasons RD mentioned. Your best bet is to find a website that you can use to better understand your test results. Most universities offer this type of thing. Research "deciphering my soil test results".
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