|
|
|
Morning Sun
  • NEWS IN AGRICULTURE: Topdressing with nitrogen fertilizer

  • For many wheat producers a topdress application of nitrogen (N) is a normal part of the wheat fertilization program.  A couple of questions are often asked during the next few weeks concerning topdressing nitrogen.  How late can we topdress wheat?  How much N is needed for the topdress application?

    • email print
  • For many wheat producers a topdress application of nitrogen (N) is a normal part of the wheat fertilization program.  A couple of questions are often asked during the next few weeks concerning topdressing nitrogen.  How late can we topdress wheat?  How much N is needed for the topdress application?
    There is still plenty of time to accomplish the topdressing task.  But don’t delay too long if the opportunity to topdress presents itself.  Even though we have suffered from drought conditions the past couple of summers, I don’t have to tell you that prolonged wet weather in the spring can sometimes make topdressing a real challenge.  We don’t have to get a lot of rain, but small frequent showers can keep the soil from drying out enough on top to allow for application.
    For growers supplying the bulk of the N program as a topdress, the application should be made prior to the jointing stage to have maximum effect on grain yield.  In most years, wheat jointing in our part of the state will start sometime in early to mid-March.  The jointing date can vary considerably from year to year depending on the weather.  Cool and wet weather will delay the wheat’s growth.  While a good stretch of warm weather in the early spring will cause wheat to start growing and jointing earlier than normal.
    We generally recommend a total (combined planting and topdress application) of 70-80 pounds of nitrogen per acre if the N is applied to the wheat prior to jointing.  However, recent research indicates that if the wheat is following a milo or corn crop last year, you should probably up that to around 100 total pounds of N to help compensate for additional crop residue.
    If you are unable to get the N on prior to jointing you can still benefit from a topdress application of N.  However, a maximum of 35 pounds of additional N should be applied after jointing begins.  Past research has indicated a 10 to 12 bushel yield response with a May 1 topdressing of wheat, however, we recommend not to topdress after the second node is visible.
    If topdressing is delayed until after wheat has started to green up and grow, application of UAN (liquid N solutions) may cause some temporary burning of leaf tissue.  This effect is merely cosmetic and causes no permanent damage.  Liquid nitrogen solutions have increased in popularity as an N source for topdressing wheat, partly because they are excellent carriers for several commonly used wheat herbicides.  Urea and ammonium nitrate are also both good N sources for topdressing wheat in late winter or early spring while the soil temperatures are still quite cool.  Ammonium nitrate would be preferred over urea for topdressing as the soils begin to warm up in the late spring.
    Cool-season grass pastures (fescue, brome, etc.) should also have nitrogen applied in the late winter or early spring.  We generally recommend about 60-80 pounds of N per acre for upland and about 80-100+ pounds per acre for high producing bottomlands.  Remember that this spring application is for spring growth only.  If you will be grazing the pasture next fall and winter it would be a good idea to apply an additional 40 to 50 pounds of N in early September.  Do not use a nitrogen fertilization at this time of year in cool-season pastures in which legumes have been interseeded.  Spring fertilization with nitrogen causes a reduction in the legume stand.  These pastures can be fertilized in September.
    Page 2 of 2 - For more information feel free to contact Wildcat Extension District agent Scott Gordon in Independence by calling (620) 331- 2690 or by email at sgordon@ksu.edu .  You may also contact Keith Martin in Altamont - (620) 784-5337, rkmartin@ksu.edu ; or Josh Coltrain in Girard - 620-724-8233, jcoltrain@ksu.edu . We also offer programs in Family Consumer Science, 4-H and Youth, and horticulture.  Program information and additional contacts can be found on our website www.wildcatdistrict.ksu.edu .
     
      • calendar