water ph and soil ph

pepper71August 28, 2010

If the PH of your water is high I am assuming it will naturally raise your soils PH? Should I lower my soils PH to counter act the high PH of the water on tap? My water tap has a PH of 8.5.

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tapla (mid-MI z5b-6a)

Garden or containers?


    Bookmark   August 28, 2010 at 10:13PM
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I am doing both , containers and in ground.

    Bookmark   August 29, 2010 at 2:57PM
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tapla (mid-MI z5b-6a)

Well - In the yard/garden/beds, you probably shouldn't be attempting to mess with your soil's pH unless you're getting strong visual indicators (signs of deficiencies or toxicities in your plants) that it's high or low. Often, adding organic matter to the soil is enough to bring pH back into line over the long term, but occasionally, other amendments might be suggested based on an analysis of your soil.

In containers - you're not going to be too successful lowering the pH of your soil, or trying to maintain any sort of consistent media pH. You CAN impact nutrient availability to a degree by manipulating the pH of your soil solution through the pH of your irrigation water. I never worry about media pH in containers, other than using some common sense in selecting how I supply my Ca/Mg. Dolomite raises pH and gypsum/Epsom salts don't (practically speaking).

In short, container media have a higher CEC than mineral soils on a bulk density to bulk density (weight to weight) ratio, but because the bulk density of container media is usually only a fraction of that of mineral soils, the CEC and buffering capacity ends up being much lower on a per volume basis. Since the buffering capacity of container media is so low, container media pH has much less affect on the pH of the soil solution than does mineral soil pH. Zzzzzzzz?. ;o)

Without very frequent testing, and the ability to inject the proper choice of acidic or basic fertilizer compounds (based on water analysis), there is no way for hobby growers to control pH to even within a whole point (5.0 - 6.0, e.g.). The pH of container media varies substantially with moisture content, fertility, temperature, fertilizer choice, ....... even the time of day and type of plant material influences pH.

.... which is why I don't bother much with media pH - only to get it in a favorable range. When you find a conventional container grower that says "I maintain my pH at ____", be suspect - especially if it's lower than 6.0.

You would expect an upward creep in pH if your water has high alkalinity (different than pH). If you're really concerned, get some pH paper and add enough white vinegar or citric acid to a gallon of water to reduce the pH to 5.8-6.0. Make a note of how much it took, and add that amount to your irrigation water and fertigation solution each time you water or fertilize ..... and forget about pH. ;o)


    Bookmark   August 29, 2010 at 3:39PM
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I grow blueberries, where I live, in Madison, Wisconsin. Our native soil has pH of 7.6, and our tap water, supplied by the city, from local wells, has considerable dissolved limestone. The tap water has pH = 7.6, also. Since blueberries need acidic soil to green up and thrive, I have to test the soil, and amend with agricultural sulfur, to lower the pH. When there is a drought, I have to water with our tap water, and yes, this does raise soil pH. However, I have never found it necessary to lower pH, in order to grow garden vegetables, like tomatoes, chard, beans, squash, basil, peppers, and broccoli. We have a raspberry patch, and that also does fine in our native soil. Its easier to grow plants suited to the native soil, but if you really want to grow blueberries in Texas, I'm sure it can be done.

    Bookmark   August 29, 2010 at 4:46PM
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so, what your saying is only option for the containers is to adjust the waters ph?
For the in ground garden I am trying to get ready for next growing season. At the begining of this year I added about 50% compost to the native soil. After a few months I got a soil test done and the PH level was at 8.1. If I am still in the high PH for the veggies I am trying to grow how can I fix this? Going with a liquid PH tester (drops kit) I am getting a reading that the waters PH is also around 8.Thanks

    Bookmark   August 30, 2010 at 12:15AM
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Your soils pH is determined by the number of free radical Hydrogen ions floating around in your soil, or the lack of them. The more of those ions floating around the lower your soils pH. The pH of your water is where it is because of the disolved Calcium Carbonate (CaCo3) in that water and like acid rain over a long period of time it might have an affect on your soils pH.
The only way to know what your soils pH is and why is with a good reliable soil test from a good soil tesitng lab that gives an indication of your soils CaCo3 and Mg levels and the ratio between them, or the need to add sulfur (or other soil acidifying agents) and how much to do what you want.

Here is a link that might be useful: About soil pH

    Bookmark   August 30, 2010 at 7:18AM
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tapla (mid-MI z5b-6a)

Pepper - it's not practical for a hobby grower to send his soil in to be tested. In containers, pH changes quickly, and there is no why you can practically maintain an even pH without many chemicals & injection equipment.

Basically, in container culture, if you put the nutrients in front of the plants they will get them. Container media pH problems are more related to a particular plant's ability to take up or limit uptake of certain nutrients than it is to pH. In other words, plants called acid-lovers don't like low pH soils because of the pH, they like it because they have difficulty limiting Ca uptake, which becomes less available as pH falls. Experiments show that if we limit the amount of Ca in the soil, you can grow happy blueberries and rhododendrons at pH levels in excess of 8.5.

For your garden & beds: you should rely on tests to tell you what is needed to lower your pH.


    Bookmark   August 30, 2010 at 11:05AM
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