Ca + MG in water

badsmerfMay 25, 2010

Hi Al! Been pretty busy lately and haven't been able to post too often (still read interesting topics that deal with soil science though hehe). I've been wondering, does the application of vinegar neutralize the natural Ca and MG in my water? Since I live on top of limerock I have a severe issue with lime build up in my water and I'm hoping that will supply enough Ca and MG along with my fertilizer for my plants. Also, I will post some pictures soon. I just repotted my key limes into a 12" pot after a few months in the gritty mix... and whoa. The root system is extremely vibrant. Nothing like the thin weak roots I'm used to seeding from plants in peat.

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tapla (mid-MI z5b-6a)

Well, it doesn't neutralize the Ca/Mg in your water in the sense that it makes them go away. What it does is work toward neutralizing the alkalinity of the water, which can lower pH and make nutrients normally difficult for the plant to absorb (because they are insoluble) at higher pH.

When we measure pH, we are measuring the concentration of hydrogen (H+) ions in the irrigation water or soil (nutrient) solution. As a guideline, water for irrigation purposes is usually best if its pH lies between 5.0 - 7.0. The measure of alkalinity gives us the water's ability to neutralize acidity. The level of bicarbonates, carbonates, and hydroxides in water determine its alkalinity. The desirable alkalinity range for irrigation water is 0 to 100 ppm carbonates, with 30 - 60 ppm optimum for most plants.

Whenever you test the water you'll be using for irrigation, you should always include the measure of both pH and alkalinity. A pH test on its own, does not give any indication of alkalinity. Water with high levels of bicarbonates or carbonates (high alkalinity) always has a pH value >7, but water with a high pH doesn't necessarily have high alkalinity. This is a very important concept because high alkalinity exerts more significant effect on plant nutrition and the fertility of growing media than pH.

High pH irrigation water generally causes no problems as long as the alkalinity is low. Since high pH water with low alkalinity has little ability to neutralize acidity, it's effect on media pH will be minimal. Cause for more concern are situations where you must utilize water having both high pH and high alkalinity for irrigation, which will cause the pH of the growing medium to increase substantially as media ages. If your water analysis is known to be alkaline, you may need to significantly reduce the addition of compounds containing Ca or Mg because of the dilute solution of limestone in the water. The smaller the container - the more serious the issue because small volumes of soil offer less buffering to pH change. In high alkaline situations, you can often expect/experience Ca and Mg deficiencies along with micronutrient deficiencies (both real and antagonistic).

Acid forming fertilizer will not actually lower media pH as long as there is limestone in the soil - unless the soil is acidic already, but vinegar (and other acid) applications will help to neutralize alkalinity in the irrigation water, which will be helpful.


    Bookmark   May 26, 2010 at 6:18PM
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Thanks Al. Exactly the explanation I was looking for.

    Bookmark   May 26, 2010 at 6:35PM
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Ok, here we are a few weeks later. I have noticed the leaves getting a slight yellow tint in them. I have a few things I think might be the cause. 1) most of the water its been getting is from the rain and so it needs more N 2) it is becoming deficient in Ca+Mg 3) overwatering, which is difficult to grasp, but it has been raining often. Thoughts?

    Bookmark   June 8, 2010 at 7:38PM
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tapla (mid-MI z5b-6a)

Have you fertilized within the last 'few weeks'? If not, it's probably a nutrient deficiency.


    Bookmark   June 8, 2010 at 8:39PM
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I have with the "everyday" dose. What should I be looking for if its the other 2?

    Bookmark   June 9, 2010 at 6:41PM
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How about you Mike, what do you think? What did your leaves look like when you watered too much? Did you ever have a nutrient deficiencies?

    Bookmark   June 11, 2010 at 5:28PM
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Hi badsmerf.....

How are you by the way..I havn't yet got to Logees!!!

When I water too much they start to turn yellow too...

But, when it rains and rains,

I think if I water with my faucet water during times of drought, the pH rises if I don't keep on top of it. So I have to add vinegar to my watering habits and they turn green again.. It is work, but worth it..

I pretty much fertilizer consistently, but if I let a week or two go by and forget, I notice a deficiency..

You know what I did different this summer as a back up, since I was afraid that I would not be able to keep up my fertilizing regimend, leaving it to someone else to water for me? I added a bit of Osmocote Plus and scratched it into the surface of most my plants..I have noticed that even if I can't get to them with my Foliage Pro as frequent as I want, and with all the watering on an almost daily basis, my plants are staying green longer...

Maybe this helps..

If I were you, just for the summer months since the temps are warm enough to make your CRF's work better, sprinkle some onto the soil and fertilize as you normaly would anyway..I am having success thus far. If you get tons of rain, your plants will still get nutrients in a slow release form to compensate for all the water flushing out the water soluable fertilizer...

Did I explain this right? I was in a rush to get out of here at work..But I didn't want to leave you hanging..

Take care...

Ps. Don't forget that temps can also ahve a major effect on nutrient uptake.. The temps have to stay above 55 at night, and below the 90's by day to keep the leaves a nice green..

Excuse the spelling errors...I had to run...


    Bookmark   June 11, 2010 at 6:12PM
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I will try to pick up some CRF. I'm going to Minneapolis this weekend so I can pick some up there. I've already been adding vinegar since I've read you had so much success with it. I could just be making something more out of it than needs to be, but if there is an issue with nutrient uptake I need to fix it.

    Bookmark   June 12, 2010 at 8:34AM
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