N during Overseeding

Discussion in 'Pesticide & Herbicide Application' started by SystemXpert, Nov 5, 2004.

  1. SystemXpert

    SystemXpert LawnSite Member
    Posts: 66

    Simple question. I did a search, but honestly couldn't find a direct answer. When you overseed how much N should be applied per 1000 sqft?

    Can I use a slow release at a higher rate? like 18-24-12 50% Slow Release and do this once in Sept and dormant feed in Dec? We are talking about tall fescue in the South.

    like 1.5N /k in Sept and 1.5N/k in Dec.

    Or should I break it up into 2 feedings. Maybe .75N/k in Sept, .75N/k in Oct and then 1.5N/K in Dec.


  2. Branchland

    Branchland LawnSite Senior Member
    Posts: 354

    I use a 18-24-12 with 50% slow release on fall overseeding. I can't tell you the rate. I just know my setting and cover the yard twice. Once in each direction. But on a 1/4 acre yard, approimatly that is, I'll use 1 bag. Sometimes 2 bags if it's a good yard, customer, and also I get to keep cutting until middle of December.
  3. Hamons

    Hamons LawnSite Senior Member
    Posts: 706

    Ok -- putting the obvious problem of not knowing your rate of application aside -- you have to be careful with products like 18-24-12. ALmost all of them contain MOP. MOP if put down too heavy has a high potential for turf damage. If you are using 2 bags on an 8k lawn -- you are putting down a pound and a half of MOP per thousand and 2.25 pounds of soluble Niotrogen --that would scare me.

    Ok -- that being said -- fertilizer makes all the difference in seeding.

    When I do my program I use 18-24-12 at about 6#/1000. I look for low slow release. Then in about 3 or 4 week use a 24-5-11 at 6# again. This will lead to some great grass. SO thats about 2.5 pounds being released in 2 months -- but the new grass will will love it.
  4. muddstopper

    muddstopper LawnSite Silver Member
    Posts: 2,342

    My personal opinion is to skip the nitrogen at the time of seeding and concentrate on the phos. levels. For me its 3lb of P per M. Then do a follow up fertilization with a blend of ammoninated nitrogen and a slow release form such as ibdu. about two weeks after seeding. One lb or 100lbs N the seed cant use it until after germination, depending on seed type and weather conditions this could be anywhere from a week to 21 days or longer.
  5. SystemXpert

    SystemXpert LawnSite Member
    Posts: 66

    Hmm..very good points. I'm planning for next year and trying to figure out what caused my problems this year. In Sept I put down .7N/k of 18-24-12 25% slow release and .5N/k of Milorganite. Then, 3 weeks later I put down another .7N/k of 18-24-12 25% slow release and another .5N/k of Milorganite. So in total I applied 2.4lbs of N per 1000sqft released in a span of about 8 weeks I think. Well, at first everything looked great! Nice dark green lush lawn, then at about week 7 brown patch started showing up. I've never had this problem before. I applied 15lbs/k of cornmeal to stop the brown patch and it worked. So now I'm researching what caused the problem. Mowing was done at 3" and watering was only done once a week deeply after the seed had germinated.

    Maybe the MOP was the problem. I read somewhere that too much can throw your soil microb activity out of balance and disease can get started. I'm also questioning the amount of N being released at 1 time, since overfertilization can also cause problems.

  6. ThreeWide

    ThreeWide LawnSite Bronze Member
    Posts: 1,116

    From reading your posts in the past, I know you have a good level of knowledge here.

    I would question your second application of 18-24-12. As one said above, that may have been too much P applied in a short amount of time. The amount of N you applied does not seem excessive.

    I have to ask you this......what did your last soil test indicate? Unless your P was low, there may have been no need to use that type of analysis.
  7. muddstopper

    muddstopper LawnSite Silver Member
    Posts: 2,342

    Brown patch occurs on dense, heavily fertilized and watered turf in hot (above 85°F), humid weather when night temperatures remain above 60°F. Poorly drained soils, thick thatch and night irrigation lengthen the period of leaf wetness and promote greater infection. High levels of nitrogen and low levels of phosphorous or potassium may contribute to increased disease severity. Mowing with a dull mower blade frays leaf blade tips and causes excessive wounding that enhances infection through those frayed blade tips. source http://ianrpubs.unl.edu/plantdisease/g688.htm#factors

    Most likely the MOP didnt cause the brown patch but the high salt levels didnt help either. The likely culprit was probably to much nitrogen. Also if your soil ph was to low,(exsisting condition or caused by excessive fertilization), the P/K that you applied might have become locked up in the soil and not been available to the grass. Somebody correct me if I am wrong because I am just guessing.
  8. ThreeWide

    ThreeWide LawnSite Bronze Member
    Posts: 1,116

    Mud, I agree with that because fescue normally needs about 4 lbs of N per 1000 per year. Considering that he put down 2.4 lbs in 8 weeks is a good recipe for brown patch.
  9. khutch

    khutch LawnSite Senior Member
    Posts: 495

    Another good fert. discussion....
    Help me out with what MOP is?
  10. muddstopper

    muddstopper LawnSite Silver Member
    Posts: 2,342

    MOP=Murate of Potash as the potassium source in fertilizer. Using sulfate of Potash, SOP, has approx. half the salt content as the MOP and will give the added benefit of some sulfur.

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