Alkaline soil

Discussion in 'Growing Organic Marijuana' started by Irie67, Jul 25, 2020.

  1. Hey Grasscity friends,
    What do you guys do to raise the PH of your soil. My plants look mostly healthy, but there is a rust color starting on the lower leaves. My water is around 8.5 and the soil is above 8 because of it. I’d like to lower the PH now but I’ve read sulphur takes months to start lowering it


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  2. you could try lemon juice to bring the pH down in your water ,,,,,mac.
     
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  3. This is a tough one, tougher than the question would lead you to believe.

    Are there plants in this soil? What time is left on this grow? How much soil volume we dealing with?

    I didn't find watering with a lower ph to help my situation.
    What did help, was pulling all the soil from my grow bed and adding in equal parts fresh Peat and perlite. Then I mixed it all up well, and refilled my beds.
    How much is probably an equation that can be solved, I just shot from the hip since I didn't need to move my soil ph as far. It's now sitting at 6.4 two months later and this bed will go back into service about 5-6 weeks from now.
    Getting the low ph water down to the root zone is for sure a problem, it's going to get buffered in the top couple inches of soil. Then you have the questions of what is making the ph high, and what will adding acid do as it dissolves the alkaline components of the soil. Are you going to have further issues with lockouts? Is the root zone ph going to be affected at all?

    Moving forward I would start ph'ing your source water beforehand, and get the soil ph in the correct zone to start with.
     
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  4. Next time premix in dolomite lime in your medium before hand and that will stabilize your ph to 6.5 during your grow. Also provides calmag


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  5. You really need to talk to @BrassNwood who has a very similar situation and uses Sulfur to correct it.

    Wet
     
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  6. I love dolo, but it would not help in this situation. It's not so much the pH of the water as it is the Dissolved Solids in the water, likely Calcium that the high pH of the water indicates that is the root of the problem.

    @waktoo also suffered with high Calcium in his water.

    Wet
     
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  7. I’m still learning more about dolo, but are you telling me that if he premixed dolomite next grow, he would have these same current problems? Or are you telling me it’s too late to use dolomite lime of his current grow?




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  8. It's the dissolved calcium in the water that's causing the problems. It just keeps adding to the lime in the soil and driving up the pH and total Calcium in the soil causing lockouts and such.

    It's certainly a water issue.

    Wet
     
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  9. Alkaline soils are neutralized with the addition of elemental sulfur, iron sulfate or aluminum sulfate.
    I chose the sulfur route and saw results in the next grow and continue to add a touch of Sulfur twice a year when I amend my in ground sites.

    Very high PH tap water and naturally alkaline western soils required a bit of an inventive solution to let me use unlimited amounts of tap water and still get a usable harvest.

    BNW
     
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  10. High levels of bicarbonates (alkalinity) and sodium in my well water, not calcium...
     
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  11. Yep definitely a water issue as I custom mixed this soil. There are currently plants in this soil in 18 gallon Rubbermaid’s. They’re autos so it should only be another 40-50 days to go. I think I’ll just stop using tap water. Sucks, but it is way too high. I’ll add some sulphur when the grow is finished to counter the damage that has already been done. Big for the rest of this grow I’ll just get clean water jugs delivered to the house. Thanks guys


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  12. Ahaaaa... My bad, don't know why I had Ca stuck in my head. I most certainly remember the struggles trying to figure out the problem till you got that water test and the cause began to reveal itself.

    Wet
     
  13. To lower the pH quickly “mulch” the top of pots with a 50/50 mix of peat moss and pine bark.

    I think it’s a good idea to know your water source before choosing how to proceed. If the problem is strictly alkalinity, you can adjust the pH of the soil as I stated earlier and then use citric acid to adjust your water.

    If you have too much Na or Cl or both in your water it requires different tactics. In this case you would want to leach your soil with clean water. RO water or a mix of RO/tap will be required.

    Compare your water to this.
    Interpreting Irrigation Water Tests

    In regards to sulfur I wouldn’t recommend it’s use indoors, especially on a small scale. The first problem like you mentioned is that it takes a long time to lower pH. Somewhere on the order of 12-16 weeks if memory serves. A bigger issue (I wish I knew about at the time) is the effect it has on microbial populations.
    An Error Occurred Setting Your User Cookie

    I run 500g beds and used 1tbs per cf of sulfur. It did get my pH in range. For about the next year I was scrambling and throwing everything in the book at em to keep the plants green. @JMcGD pointed out a similar study to me a few months back. I concentrated on building a nice mulch layer and paying more attention to the teas I was making. Everything seems to be jamming along now.
    RD
     
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  14. #14 JMcGD, Jul 29, 2020
    Last edited: Jul 29, 2020
    I have the same issue, severe levels of bicarbonate. The way I understand it that will “react with the Ca and Mg in the soil to form insoluble calcium carbonate and magnesium carbonate (lime).”
    Here’s a good link for info on interpreting a water test for irrigation purposes.
    https://agsci.psu.edu/aasl/water-te...ur-turf-irrigation-water-analysis-report-wt02
    I struggled with high alkalinity and pH in my beds for quite awhile. I took some time but the addition of unlimed peat like @Nosmatt as a top dress seems to help , and when I added two light dosages of sulfur over three months that really did the trick. I went from a soil pH of 7.5 to 6.6.
    I’m still seeing some crazy leaf tip distortion, @waktoo made me feel better though by showing me that he had the same issue as I do. IMO that particular issue has to be a result of the bicarbonate causing some sort of calcium deficiency, so I’ve been playing with my concentration of RO water to tap water.

    edit: sorry for the double info, I started this post yesterday and got distracted and never finished it. Glad you chimed in RD!
     
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  15. @chapora check out this thread

    cheers
    Os
     
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  16. I never really did solve this problem. I switched to RO water but I’m at the end of my run and my plants have severe discoloration. The buds all got fat which is great. So I got a decent harvest, but none of them were healthy. Would you guys recycle this soil or start fresh? Could I start with fresh soil for the next run and, in the meantime, put this soil in a pile and let it cook? Will the ph come down and be good to reuse after a few months?


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  17. There are a few replies just above your post about what others ha e done to remedy the situation.
    I chose to remove all my soil and mix in fresh Peat, then repotted and cooked for three months.
    My new plants are doing fantastic, but they have not flowered yet. I cannot say my issue is solved for two more months. My ph slurries have been very consistent at 6.6.
     
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