Ph measurements"meter or paper?

Discussion in 'Pesticide & Herbicide Application' started by basic lawn, Mar 13, 2003.

  1. basic lawn

    basic lawn LawnSite Member
    from nj
    Posts: 50

    How do you guys prefer to measure soil Ph? What is a good way to take samples.

    Do's and Do nots? Regarding soil corrections from being too acidic--, is there a formula that you guys use to calculate lime per area necessary?

    I appreciate answers from you soil chemists out there...
    and from veryone else.

    thanks in advance,

    Basic Lawns
  2. EJK2352

    EJK2352 LawnSite Bronze Member
    Posts: 1,150

    I use CLC labs., they are located in Ohio. I have found the meters are inaccurate. :) ;) :) ED
  3. HBFOXJr

    HBFOXJr LawnSite Bronze Member
    Posts: 1,712

    CLC Labs or by a Cardy pH meter that requires you to mix up a solution and place it on a special meter. Pretty darn accurate. However the tests that CLC does also gives the buffer pH which can differ from soil pH and change requirements of acid soils.
  4. stslawncare

    stslawncare LawnSite Bronze Member
    from DE
    Posts: 1,484

    i actually borrowed a meter from a friend that he got real cheap and it was very accurate, could have been chance, i dont know.
  5. Ric

    Ric LawnSite Fanatic
    Posts: 11,956

    What is pH

    pH is the inverse logarithm of the hydrogen atom in a solution.===>Soil in water is measured for the amount of free hydrogen ions. SOIL IN WATER is the key words here for proper measurement. The water must be a "mole solution" in order to get a proper reading. Therefore chem labs can do better reports. However lab to lab, tech to tech the answer will be different. With a good pH meter and a Mole Solution you can get just as good of a result. However this requires a little chemistry and knowledge there of. pH meters must be calibrate. with a buffer agent first.

    pH is the inverse logarithm of the hydrogen atom in a solution.===>Soil in water is measured for the amount of free hydrogen ions.

    The more hydrogen ions the lower the pH.==> acid
    The less hydrogen ions the higher the pH==> Base or Al-kine

    My soil runs 8.5 to 9.5 pH therefore I use ammonium sulfate as my nitrogen source to help lower pH. This works two ways 1.) ammonium sulfate is 1.333 lb sulfur to 1 lb of nitrogen. Therefore for every pound of N I am putting down 1.333 lb of sulfur. 2.) ammonium is 1 part Nitrogen to 4 parts Hydrogen. Therefore for every atom of Nitrogen I put down I am putting down 4 atoms of Hydrogen. The Increase in hydrogen ions decreases pH .

    If my soil were 4 to 5 pH I would put down lime to raise pH. Here is how it works. Lime has hydrogen oxide or OH. OH joint with the free Hydrogen atoms to form HOH or water H2O. The decrease in Hydrogen ion increases pH.

    Sorry I don't put down lime or dolomite and forget the formula. I am too lazy to look it up right now. However I do remember that 50 lb per thousand is most you would put down in a given period of time. You can not change the pH. unless you amend the soil. therefore lime is only a temp fix.
  6. Russ

    Russ LawnSite Senior Member
    Posts: 539

    I have a Spectrum Technologies "PH PRO". It recommended that recalibration is made prior to every measurement.
  7. Ric

    Ric LawnSite Fanatic
    Posts: 11,956


    Even the high priced Lab models need to be re calibrated every time. So it sounds like you have a real good pH meter. Most pH meters are re calibrated with a buffering agent or a solution with a known pH. Some chemists will use distilled water to mix the soil with and other use a Mole Solution ( special salt water ). Therefore pH reading will differ. Water quality plays an important roll and volumes have been written about water quality and its effect on our plants.

    pH can be different at 2" deep and 6" deep etc. Soil Chemistry is one of the most complex sciences there is. It is forever changing.

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