Soil Analysis results

Discussion in 'Pesticide & Herbicide Application' started by mac43rn, Jul 23, 2007.

  1. mac43rn

    mac43rn LawnSite Member
    Posts: 237

    I have a lawn which I just recently acquired. I recently took a soil sample using a soil probe and wanted to post my results here to get some advice. My local Lesco dealer said everything looks fine, but I am a bit concerned about the pH and the look of the lawn.

    Lawn type: Tall Fescue
    Soil type: Clay

    pH - 7.7
    Buffer pH - not listed

    Mg- 881

    Calculated Values
    Cation Exchange Capacity- 19.2
    Ca - 79
    Mg - 19

    The biggest problem the owner states he is having is getting a nice green lawn, even after an application. The lawn is irrigated so and the area has had its fair share of rain. What would be the best plan of action to getting the lawn pH down around 7.

  2. tremor

    tremor LawnSite Bronze Member
    Posts: 1,476

    Sulfur to reduce the pH. Five lbs/1000 at regular intervals until the pH is corrected. I don't see a percent organic matter but I'll wager it's low. If adding organic materials is out of the question then you might consider Gypsum to shake up the clay.

    Then starter fert & overseed top shelf varieties if it's thin.
  3. lilmarvin4064

    lilmarvin4064 LawnSite Senior Member
    Posts: 757

    also, I bet some chelated iron and micros would help deepen the green.
  4. muddstopper

    muddstopper LawnSite Silver Member
    Posts: 2,342

    First you need to look at what is driving your ph. If you look at the saturation levels of nutrients, you will see that the 2%k, 79%Ca, and 19% Mg total up to 100%. This doesnt leave you much room for any other nutrients, including Hydrogen, which is what frees up the other nutrients. The Ca and Mg is what is driving the ph up. The use of acidfying fertilizers such as Ammonium sulfate, will lower the ph pretty fast, and it will help lower the saturation levels of Ca and Mg. Also the use of SOP will not change ph much, but will raise the K levels in the soil and also provide additional sulfur to help lower the Ca-Mg saturation levels. Once the saturation levels are reduced to around 3-5% K, 68-70% Ca, and 10-15% Mg, your ph should be reduced allowing a percentage of the CEC to contain more H. As H saturation levels raise, other nutrients will become available to the plants.
  5. jrc lawncare

    jrc lawncare LawnSite Senior Member
    Posts: 420

    That is some good info there, thanks for sharing. It's interesting that too high of a ph will lock up nutrients in the soil, only released by lowering the ph. Probably a lot of people out there that don't even know that. Good post.:)
  6. mdlwn1

    mdlwn1 LawnSite Silver Member
    Posts: 2,443

    I'm relieved to hear that someone doing business out there knows this stuff. Too bad you don't do apps by me...wah wah
  7. mac43rn

    mac43rn LawnSite Member
    Posts: 237

    Where can a find a ammonium sulfate based fertilizer? I looked at the labels of a few lesco products and they contain very little ammonium sulfate? Any help would be greatly appreciated.

  8. Harley-D

    Harley-D LawnSite Senior Member
    Posts: 508

    I'm pretty sure it would take you forever to lower your ph one point if you only rely on sulfur coat fert or ammonium based ferts. Mudd will have a good answer but your cheapest and quickest way is probably sulfur dusting. Especially if you want to see some results in the next year. Google-sulfur to lower soil ph

    My question to mudd...are there any harsh side effects to that much sulfur at one time? Some of the charts i've seen, it would take forever to adjust ph one point just using fert. Typ-3 50lb bags fert/acre is equivilant to just three bags of lime per acre to neutralize the fert's acidifying effects. Is this true? Thanks for the info mudd.
  9. muddstopper

    muddstopper LawnSite Silver Member
    Posts: 2,342

    You are correct in that the sulfur in the fertilizers would take a long time to start changing the ph, but the sulfur in fertiliers is in the sulfate form and much more readily available to the plants than elemental sulfur. It takes 3 lbs of sulfate sulfur to equal one lb of elemental sulfur so if you rely on just the sulfates in the fertilizers, it will take a large amount to correct the S levels in the soil.

    As for adding large amounts of elemental sulfur, you can expect similar results to adding large amounts of lime. The elemental sulfur is going to take several weeks to break down to the sulfate form and/or translocate down into the soil. What you will have is a very acidic ph right at the top of the soil, with very little change down in the root zone. If you are incorporating the sulfur, its the same as with lime, you can add the entire needed amount at one time, but if you are not incorporating, you should only add 15% of the suggested amount for evey inch in depth of the soil that you can influence. For topdressing or broadcast applications, 30%-45% in the first application and then followup applications until you have applied the entire recommended amount. In all honesty, acre S levels are usually recommended in the 60-80 ppm range which translates into 120-160 lbs of total S on one acre of soil 6 inches deep. Your soil probably already has at least a portion of this amount and applying the entire residual amount at one time probably wont do any harm.

    Sulfur is usually listed in the elemental form on soil test so the amounts suggested is the amount to apply. If your soil test list sulfur as SO4, then it is in the sulfate form and elemental sulfur amounts should be divided by 3 to determine just how much actual S to apply. This also works in reverse, if you are using sulfate forms, then multiply by 3 to determine how much you need to apply to get the total amount of S.

    Sulfur leaches easily, so once the correct S level is reached, using fertilizers that contain SO4 will help maintain the S in the correct ranges.
  10. rcreech

    rcreech Sponsor
    Male, from OHIO
    Posts: 6,057

    Mudstopper makes some good points, but be careful when adding S to your lawn. You can get a S burn if you apply to much (or how much it would actually take to drop your pH). OSU states that if your pH is below 8 (for lawns), then no altercation is needed. Read the sites below from Purdue and A&L Labs as neither one recommends adding S to drop pH in an existing lawn.

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