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Late season iron application

Discussion in 'Fertilizer Application' started by LawnsharkMB, Feb 10, 2013.

  1. LawnsharkMB

    LawnsharkMB LawnSite Senior Member
    Posts: 582

    In the past I've always made two fertilizer apps to centipede lawns. 15-3-7 SCU in the spring and 10-0-20 SCU in the summer.

    This year I was thinking about changing it up a bit and putting down 21-0-0 ammonium sulfate in the spring, and then putting down a slow release in early summer and then just doing a late summer iron application for color.

    What do you guys think about this and is iron something you use a lot? Also, I've read that it's not good to put down iron when the temps are high. It will be in the 90's here in August when I plan on making the iron application.
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  2. ToddH

    ToddH LawnSite Silver Member
    Posts: 2,184

    I do not know much about centipede except it has low requirements. Iron is what adds the color so why just in the fall?
  3. LawnsharkMB

    LawnsharkMB LawnSite Senior Member
    Posts: 582

    Only 2lbsN/K per year on centipede. The 21-0-0 will be put down at just under a pound and the early summer app will be a pound of slow release. That will put me at the max for the year.
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  4. ToddH

    ToddH LawnSite Silver Member
    Posts: 2,184

    I think N and K at 2:1 plus some iron is the magic formula from what I have read here as well as based on some trials at A&M. Reduces weeds too.

    I have no problem using a granular slow release in the summer either to substain the color for a few months.

    Might consider 1/2 Pound N .25 K with an Iron pack twice a season spring and fall with an early summer slow release of 1 pound.

    I tried a heavier dose of AS in the fall last year and scorch a couple of lawns. I will not go over 1/2 pound and may stay closer to .33 and rely on the Iron for color and the slow release for the big N. I will be doing a min of 4 N sprays however plus the slow release.
  5. RigglePLC

    RigglePLC LawnSite Fanatic
    Posts: 12,215

    I agree with ELS, water soluble ammonium sulfate at a heavy rate could burn the grass and if you ever have heavy rains, it would be lost too quickly--leached out, or into the deep ground water. Wouldn't you be better off with a slow release N source? You would get a little more nitrogen for green, every time it rained. I agree with ELS, in that a half-pound of slow release nitrogen plus some potash four times per year would be my choice. Include fall application. But then, I am 1000 miles away and buried in snow.

    I see a similar problem with the 10-0-20. The potash would be leached out after about an inch of rain. You should include potash in both applications. Better still--all applications--water soluble, it does not last long.

    Include lime as needed according to soil tests. Am I right, when I think centipede does fine on mildly acid soil?

    Remember iron stains turf a blackish green color. Be ready to accept the look. Be ready to accept that it does not last long after the stained leaves are mowed off. I have not heard that high temperatures are a problem for iron applications, (but its cold here).
  6. ToddH

    ToddH LawnSite Silver Member
    Posts: 2,184

    Heavy Iron does make the grass look a little funny but in correct portions it makes it deeper green that will last for 4 to 6 weeks.

    I have been trying to tweak my program for a while now.

    I am going to use some AS and POS at 2-0-1 and apply frequent low hits. The slow release is for summer.
  7. LawnsharkMB

    LawnsharkMB LawnSite Senior Member
    Posts: 582

    Centipede does like a lower ph. 5.5 -6.0 range seems to be ideal. The early summer app will be Allectus 18-0-8. The max rate of the insecticide will give you 1lbN/K slow release. I guess I will go with 1/2 pound AS for green up, come back a few weeks later in early June with the allectus 18-0-8, and then maybe 10-0-20 w/10% iron in early August.

    Riggle you said an inch of rain and all the potash would be gone? Centipede needs an inch of water per week preferably all at one time. Does this mean my slow release fertilizer is only gonna last a week if my customers are watering their lawn properly?
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  8. RigglePLC

    RigglePLC LawnSite Fanatic
    Posts: 12,215

    Slow-release refers to the nitrogen. The potash is not slow release, (not normally). Unless it is definitely printed on the bag that you have slow-release potash--its quick-release potash. I hear centipede is very finicky-none in my state, of course.

    Be sure you are applying the Allectus at the proper time--around here July is preferred. Shop around--try to find an Allectus product with much less nitrogen. Such as the Anderson product...

    Also watch out for slow-release exaggeration. The front of the bag may say 50 percent is sulfur coated urea. And the back of the bag in the fine print may say 20 percent nitrogen, of which 10 percent is sulfur coated, and then finally 7 percent is water insoluble. (Because some of it is sulfur, it is normal for SCU to be 38 percent nitrogen, incomplete coatings and broken granules reduce the actual slow-release nitrogen portion).

    Read the label carefully--with a skeptical eye. Comparison shop. Maybe an organic or slow-release plus organic would suit you best during the hot summer. Talk to Barry...Phasthound knows his stuff.

    Myrtle Beach--does that mean it is sandy soil? Red clay? An inch of water might dissolve the potash, and some of the uncoated nitrogen, but the remainder of the nitrogen would be gradually released over the next few weeks.

    Read up on the micronutrient needs of centipede on your type of soil. You might consider submitting a sample of soil for the full costly full micronutrient analysis. Tissue tests for micronutrients are better--after all you could be short on manganese, zinc, copper, boron...who knows?

    Perhaps people near you can advise you better. Your competition in your local area may not want to chime in.
    Last edited: Feb 10, 2013
  9. turfmd101

    turfmd101 LawnSite Bronze Member
    Posts: 1,289

    Try LESCO 12-2-14 70% slow N & 70% slow K. 4.5 Fe good Mn and Mg. Two times annual, maby three times.
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  10. greendoctor

    greendoctor LawnSite Fanatic
    Posts: 9,064

    N without anything else can be trouble on centipede unless the soil has adequate K. On centipede, I prefer to apply N, K, and micronutrients all together. No chlorides and no P in the fertilizer. How long is your growing season such that 2 applications will do it? I do agree with using ammonium sulfate as the N source. That has the added benefit of supplying S and aiding in the maintenance of an acid soil pH. Sadly, the only way to reliably get a fertilizer that does not use urea and muriate of potash as nutrient sources is to blend your own. That is what I do in the tank and spray the mix on in 5 gallons. There should be no need to apply 1 lb of N at a time, I get good results applying 1/2 lb N at a time to centipede. .

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