Late Fall fertilizer 46-0-0 or 21-0-0

Discussion in 'Fertilizer Application' started by redskins4ever, Oct 20, 2007.

  1. redskins4ever

    redskins4ever LawnSite Member
    Messages: 2

    I am new to the board so I appoligize in advance if this topic has been discussed before. I operate a lawn care business in Northen Ohio and was thinking about applying a late Fall fert with a 1.5 pounf of N.

    whats your thoughts of using 46-0-0 ( urea) vs 21-0-0 Ammonuim sulfate?
  2. Runner

    Runner LawnSite Fanatic
    Messages: 13,497

    the 46 is just too much N to be going down in the fall for your area. What yo want to look out for, is the flush of growth - going into the cooler season, that can later allow fungus and other problems to rise. We go no higher than 32, here....and ultimately LIKE to make sure it has SOME time to store some of this (after growh has declined but before dormancy has set in).
  3. MStine315

    MStine315 LawnSite Senior Member
    Messages: 789

    But, if you do it later in the fall than now, like closer to mid-November, I personally think the 46 is OK. Joe is right, if you do it now, the turf won't naturally harden off and stay succelent going into cooler, wetter weather and maybe even into snow cover. You want the plant to naturally slow down, top growth to stop, then hit it, when the roots will still take it up and store it without using it. My concern is the 1 1/2 lbs. Why not just a pound? There are a couple of really good 8-10 page threads on here about dormant feeding with pros and cons of various methods. I would browse through those to maybe help sway you one way or another. There are many ways to skin the cat that is fall fertilization.
  4. ThreeWide

    ThreeWide LawnSite Bronze Member
    Messages: 1,116

    In cooler temperatures, there is a certain point where 46-0-0 will be much less effective than 21-0-0. The reason is that the Urea needs to be converted into usable form, and that conversion process slows significantly in cooler temps. If the temps are too cold, the Urea will be leached and gone prior to utilization. Ammonium Sulfate does not need to go through the same conversion process, so it is more effective in cooler temps. Both of these will push shoot growth if the temps are warm enough. Either way, I would think more than 1 pound per M would be overkill.

    I won't try to comment on the Winterizing concept, since that is not something we deal with in my area.
  5. redskins4ever

    redskins4ever LawnSite Member
    Messages: 2

    Thanks for the replies, the reason I thought about using 1.5# of N is to give the lawn a "Boost" in the spring. Our lawns have had a very stressful summer/Fall so I want to impress the Homeowners next Spring with a beautilul lawn
  6. lescojdl

    lescojdl LawnSite Member
    Messages: 40

    I would use the 21-0-0 if you have a sulfur deficiency or soil pH over 7. If you want to do a winterizer before top growth stops, try using something with a slow release N that does not rely solely on temperature or microbial activity to release, such as SCU, PPSCU, or IBDU. Examples are 32-3-8 30%PPSCU 3Fe or 32-5-7 50%PPSCU. You would be safe putting down a higher rate of N than 1lb per M since half or a third of the N is released later. Make sure you or the homeowner waters the product in if sprinklers have already been turned off when you apply a 46-0-0 or 21-0-0. Good luck.
  7. FdLLawnMan

    FdLLawnMan LawnSite Bronze Member
    Messages: 1,253

    I have been putting down 46-0-0 the past years with excellent results and no more disease problems that any other lawn. If you apply it around the last time the lawn is mowed you will be perfect.

    Mike I
    Mike's Total Lawn Care
  8. group501

    group501 LawnSite Member
    Messages: 174

    30-0-15 all mineral at 4# per 1,000 sq ft. Excellent results, product cost is inexpensive.
  9. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 13,808

    I think 1.5 pounds is too much. Remember that a heavy rain event may wash some of this into lakes or streams. Also a heavy shot of quick-release nitrogen will find its way into ground water. Experiments at Michigan state University using soil-in-place lysimeters--measured the amount of nitrogen leaching out at 6 feet deep in the soil. Regular lawn care probrams were OK. As I recall the main problem resulted when heavy fall fertilization followed a regular fertilizer program. The nitrogen was not absorbed by the roots, and was followed by a heavy rain event. This allowed excess nitrogen to enter the ground water at the 6 foot deep level. They sometimes got levels up to 20 parts per million. As I recall the limit for drinking water was about 2 parts per million.

    Green up in spring needs fertilizer--HOWEVER--much of that green up depends on the soil temperature and the grass species and cultivar. Some sod-type Kentucky bluegrasses green up 14 days later than some types of ryegrass.

    Myself I am often back on the lawn applying crabgrass control with fertilizer in spring before greenup occurs.
  10. Grandview

    Grandview LawnSite Gold Member
    from WI
    Messages: 3,251

    If using 46-0-0, just use 2.5 pounds per thousand and you are just fine. The cost per pound of N is probably the cheapest also.

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