Late N app no more?

Discussion in 'Pesticide & Herbicide Application' started by fall46, Nov 8, 2010.

  1. fall46

    fall46 LawnSite Member
    Posts: 141

    Maybe this has been covered, I'm late this year in getting my last .50 lb of N down. In Twin Cities But I just stumbled on this. What do you think? (scroll down for lawn section)

    New research results from the University of Minnesota and the University of Wisconsin-Madison necessitate updating our current lawn/turfgrass fertilizer recommendations. For the past 20 to 30 years, one of the more important fertilizer application times was considered to be the end of October and into early November in the Twin Cities and southern Minnesota. Indeed, lawns respond positively with good green color and active growth significantly earlier the following spring when given about 1# of N per 1000 square feet late in the previous growing season. This application came to be known as a late fall or more accurately a late season fertilization. In most years, this typically coincided with about the last mowing of year and with hoses put away or irrigation systems winterized for the year.

    Even though this research was conducted on creeping bentgrass these findings demonstrate that nitrogen uptake late in the season is significantly less than when applied around Labor Day to the middle of September. So, what happens (or potentially can happen) to the remaining nitrogen not used or taken up by the grass plants? Other recent research on Kentucky bluegrass at Michigan State University points to increased leaching of N fertilizers when plants are not actively growing which is often the case with the late season fertilization. Nitrogen can also be converted to a gaseous form and lost back to the atmosphere. In some situations it can even be lost through runoff, particularly when soils are frozen. Some may also be taken up by other landscape plants that happen to share the same rootzone as the turfgrass (e.g., trees and shrubs).

    So, back to our original question, "If only a small portion of available N is utilized by the grass plant, what happens to the rest of it?" A more complete answer to that question rests with additional research which is ongoing. Nonetheless, available and unused nitrogen can pose additional environmental risks as noted above and be uneconomical for the user. After all, no one wants to be spending money on fertilizer and the labor to apply it if only a small fraction of that material is being utilized by the grass plant with the rest potentially being wasted.

    It should be noted that results from the University of Minnesota soil testing lab may indicate significantly less nitrogen be applied on an annual basis depending on information provided about the care and use of the turfgrass area tested as well as the level of soil organic matter present. Leaving clippings on the lawn typically results in about one application of a complete fertilizer (i.e., a fertilizer containing nitrogen, phosphorus and potassium) annually back to the lawn. Hence, when clippings are returned, the amount of nitrogen needed is also reduced. The four options below assume clippings are returned to the lawn.
  2. grassman177

    grassman177 LawnSite Fanatic
    Posts: 9,795

    well, the turf responds to it and i am not going to stop
  3. wrgrounds

    wrgrounds LawnSite Member
    from WI
    Posts: 34

    Not going to change my mind any. I'd hate to try to fit in my last app around Labor day. I have to many other things going on. I should be finishing tomorrow.
  4. JD2320

    JD2320 LawnSite Member
    Posts: 132

    It will change your mind to some extent when your areas get restrictions on how late you can apply fertilizer, or how soon you can start in the spring like we have here in my area.

    We can't apply after 11-10 and or when the soil temps hit 38 degrees whichever comes first and can't start until April 1st, or when soil temps break past 38 degrees.
  5. wrgrounds

    wrgrounds LawnSite Member
    from WI
    Posts: 34

    In our area I would almost have to agree with those restrictions. Anything between Mid Nov and April would just sit on the ground and run off with the spring thaw. I hate restrictions though, maybe just a strong suggestion for a rule of thumb.
  6. grass4gas

    grass4gas LawnSite Senior Member
    Posts: 473

    No nitrogen can be applied here after 12/7 or before 2/15 regardless of how warm or cold it might be.
  7. paponte

    paponte LawnSite Silver Member
    Posts: 2,366

    Went into law 2yrs ago here, no N between Nov. 1 & Apr. 1. They also require a N fertilizer course be taken in order to keep or apply for a Business License.
  8. lilmarvin4064

    lilmarvin4064 LawnSite Senior Member
    Posts: 757

    I'm sure it all depends on the temperature. A few years ago I did an application of fert in the 1st/2nd week of January, and noticed a definite response (greening + a little topgrowth) on fescue. Of course it was a warm spell, upper 40s/low 50s I think, and I'm farther south than most of you.
  9. mdlwn1

    mdlwn1 LawnSite Silver Member
    Posts: 2,443

    Northeast only.......Under normal circumstances/weather etc...a heavy fall app is only to ELIMINATE a spring app. Defining heavy, well thats a whole different discussion.
  10. mdlwn1

    mdlwn1 LawnSite Silver Member
    Posts: 2,443

    Dog poop will green an area in during temps WELL below 40 if you give it enough time.

Share This Page