soil test results for my centipede lawn

Discussion in 'Homeowner Assistance Forum' started by Iexpedite, Sep 12, 2019.

  1. Iexpedite

    Iexpedite LawnSite Member
    Messages: 18

    I posted a few weeks back "to sedge or not to sedge". I was looking for advice on applying sedgehammer to my new lawn. At that point, I had some questionable results from a home soil test. I got a real soil test and the results are as follows:

    I pulled two sample sources, front/back yard and side yard. I split it up after finding a lot of red fill sand that was trucked in for the foundation on the side yard.

    Front/Back

    "Soil pH is 6.2
    Phosphorus 122 lbs/acre (High)
    Potassium 172 lbs/acre (Medium)
    Magnesium 64 lbs/acre (High)
    Zinc .1 lbs/acre (Very low)
    Calcium 1530 lbs/acre

    Therefore, the following recommendations are suggested :
    ** All recommendations are per 1000 square feet. **
    Approximate Date Rate and Type of Fertilizer
    Apr 1 3.0# 34-0-0
    2.0# 0-0-60 (Muriate of Potash)

    Aug 1 3.0# 34-0-0
    1.5# 0-0-60 (Muriate of Potash)

    Sides

    Soil pH is 7.4
    Phosphorus 46 lbs/acre (Medium)
    Potassium 110 lbs/acre (Low)
    Magnesium 73 lbs/acre (High)
    Zinc 2.6 lbs/acre (High)
    Calcium 3005 lbs/acre

    Therefore, the following recommendations are suggested :
    ** All recommendations are per 1000 square feet. **
    Approximate Date Rate and Type of Fertilizer
    Apr 1 3.0# 34-0-0
    3.0# 0-0-60 (Muriate of Potash)

    Aug 1 3.0# 34-0-0
    2.0# 0-0-60 (Muriate of Potash)"

    In my original post, I was instructed to apply Tiger90 Sulfur to lower the PH. There was no mention of PH correction in my lab results. However, I think applying Tiger90 is a good idea.

    The results recommend adding Potash to increase Potassium levels (sandy soil) and nitrogen. Any other suggestions? Is one source of Nitrogen or Muriate of Potash better than another?

    original post
    https://www.lawnsite.com/threads/to-sedge-or-not-to-sedge.491491/page-2#post-6084626
     
  2. takervader

    takervader LawnSite Senior Member
    from Alabama
    Messages: 484

    It appears the tester did not care about what the soil crop actually was, and just made a recommendation based on agricultural norms, otherwise they'd have mentioned pH.

    But for both of your areas tested, you need to lower the pH. Centipede likes it at 5.5. At 7.4 it will not be happy and likely will not be the right shade of green due to it not being able to absorb iron well.. Start applying Tiger90 every few months to both until the soil results for the 6.2 area is down to 5.5, then continue on for the other area until it does as well. It will require quite a LOT of sulfur to lower the pH in the 7.4 area and you want to just get started now. It will be a gradual process over several years. The soil probably could not absorb it at all if you tried to do it all at once, and it would be a very high amount of sulfur for you to buy and put down.

    I would put down 15-0-15 with at least 50% slow release N twice a year, once when its all green which will be likely Mar/Apr, another around July 1. I would never put down a 34-0-0 on centipede at once. Bermuda and zoysia? yes, not centipede. It won't use it. Urea are fast release, but its hard to find something that is solely Ammonium sulfate or MESA, so a mix is about the best you'll find. Just look for mostly slow-release on the bag.

    For fall, the 0-0-60 is fine if the soil test is showing that you need it. It will be healthier next year. You can use muriate of potash (potassium chloride) or potassium sulfate as the source and I would use the sulfate version myself. Likewise as N above, finding a granular without KCl in it can be tough.

    At this point I wouldn't be very concerned about the source of the N and K and would recommend you find a good brand of fertilizer with just the 15-0-15 ratio or something close to it, like a Lebanon 17-0-17. I'd switch over time however, and be sure to not add P.
     
  3. OP
    OP
    Iexpedite

    Iexpedite LawnSite Member
    Messages: 18

    A few months ago my lawn was an overgrown woodlot. I have been watching them install sod on the homes around me and I haven't seen them put any fertilizer down pre-sod. It's possible I missed it but... I put down 13lbs per 1K Milorganite late August. One possible source. I live less than two miles from the Gulf of Mexico. Not far from where the Mississippi River meets the Gulf. Those waters are known for being nutrient-rich. I wonder if that could be the source?
     
  4. OP
    OP
    Iexpedite

    Iexpedite LawnSite Member
    Messages: 18

    I have a few follow-up questions for you. It looks like the potassium sulfate has a sulfur component that would help with my PH issue. That sounds like a plan.

    As for the tiger90. From my reading, I should only apply 10# per 1K, per year. Up to this point, I am answering my own questions but am I headed in the right direction?

    You mention switching to 17-0-17 over time. I'm not completely sure what you meant by that.

    Lastly, I found the products you mentioned online. Do most people end up ordering this stuff? I have done a cursory search and I am not finding local dealers.
     
  5. takervader

    takervader LawnSite Senior Member
    from Alabama
    Messages: 484

    I mean that Centipede tends to tolerate KCl up to a point where the Cl doesn't leave the soil and ends up weakening the grass. That point may be 10 years from now, may be never for some folks. You'll find that most granulars are KCl, not K2SO4. So, in the interest of you finding what you need locally, I wouldn't worry about it yet. Likewise for the nitrogen compound used to deliver to the soil. Just find the 15-0-15 ratio or something like it, it just needs fairly equal N and K, no P. Lebanon 17-0-17 is a specific brand I'd look for that I know is made and is good fertilizer.

    What you need to worry about most is getting the pH down. K2SO4 helps but its the Tiger90 that you need to get you there. Every 3-4 months, put some down.
     
    hort101 likes this.
  6. OP
    OP
    Iexpedite

    Iexpedite LawnSite Member
    Messages: 18

    I found a source for Tiger-Sul 90CR and Sulfate of Potash 0-0-50. I ordered 1 bag each. I'll get it put down when weather permits. My application rate will be on the light side. My lawn budget is buckling under the late-season strain. When spring arrives I start back with new money and heavier applications of Tiger-Sul. Then I'll get started on my fertilization with equal parts N and K (slow-release).

    Thanks for the direction...
     
  7. OP
    OP
    Iexpedite

    Iexpedite LawnSite Member
    Messages: 18

    Scratch that, I ordered two bags of Tiger-Sul 90CR.
     
  8. takervader

    takervader LawnSite Senior Member
    from Alabama
    Messages: 484

    You can still apply the Tiger90 in winter as the lawn is dormant, you dont necessarily need to wait until spring.
     
    That Guy Gary likes this.
  9. That Guy Gary

    That Guy Gary LawnSite Gold Member
    Messages: 3,008

    The elemental sulfur is the correct product, sulfate sulfur is ph neutral.

    Elemental sulfur is metabolized into sulfuric acid by microbes. The acid reacts with calcium carbonate in the soil to become gypsum, this is the long term effect of elemental sulfur on ph.

    Soil type influences how much is needed for a substantial effect, I think it ranges 5-15 lbs per k on average, going from sandy to clay on the spectrum.

    Other factors like how hard the irrigation water is can impact it.

    It's good to get some down late/fall early winter, so it has time to work into the soil and be available for microbes in the spring.

    It's also hard to burn the turf with it when it's dormant. They say not to put down more than 5 lbs per k when it's active, I've done 10 lbs per k on cool season turf in November.

    Except to see actual results from the sulfur when there's been about 6 months of active growth since applied.
     
    hort101 likes this.
  10. OP
    OP
    Iexpedite

    Iexpedite LawnSite Member
    Messages: 18

    This is my first winter here but I know the temps don't get real cold. I don't know how much of a dormancy I will get.

    Guy Gary, I believe this is the correct approach as well. Not that I know anything but my due diligence supports the information.

    My plan of attack is to put down 5lbs per thousand Tiger-Sul. Then wait a month and reapply. I'm not completely sure when to start. Temps here are still in the 90's every day does it matter? The calculator says I need 15lbs per 1k to lower my 6.2 down to a 5.0. I probably will only apply 10lbs this fall and another 5lbs in the spring.

    The side yard is difficult because I know that the high PH soil (7.4) isn't everywhere. The closer you get to the house the more there is. I think the best approach is to get the high PH soil down below 6.0 (4 applications) which would make the normal side soil drop down to a 4.7 still within range.

    The Sulfate of Potash will go down at 2lb of material per 1K. Which equates to 1lb of actual Potash. I will put it down a few weeks after the Tiger-Sul. Then in the spring, I will put the Potash down again at that same rate.

    Is this a workable plan and should I start now or wait for cooler temperatures?
     

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