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Morning Sun
  • NEWS IN AGRICULTURE: Manage alfalfa stands through the winter

  • Alfalfa, when managed correctly, is a potentially profitable crop for southeast Kansas.  Alfalfa requires a great deal of management to be successful.  Even while the alfalfa is dormant, we can be managing for next years crop.  Soil fertility and weed control are two of the areas we can work on this winter.



    Now is the time to soil test for the alfalfa’s 2013 fertility needs.

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  • Alfalfa, when managed correctly, is a potentially profitable crop for southeast Kansas.  Alfalfa requires a great deal of management to be successful.  Even while the alfalfa is dormant, we can be managing for next years crop.  Soil fertility and weed control are two of the areas we can work on this winter.
    Now is the time to soil test for the alfalfa’s 2013 fertility needs.
    Phosphorus and potassium are the two elements that are normally added to established alfalfa stands.  
    Soil testing is available through the Extension office at a cost of about $7.00 per sample.
    The soil does not need to be completely dry in order to take a routine soil sample.  Contact the Extension office for more information and soil sample bags.
    Nitrogen applications should not be made to established alfalfa stands.  Legumes, such as alfalfa, fix enough nitrogen to meet the needs of the growing plant through bacteria present in the nodules on the roots.  Nitrogen fertilizer applied to well-nodulated alfalfa will only stimulate grassy and broadleaf weeds and may reduce stand longevity.
    Broadcasting phosphorus has proven effective on soils low in phosphorus because alfalfa has roots near the soil surface.  Topdressing is normally done in the late fall to early spring.  
    Little difference exits between liquids or solids, or ortho or polyphosphates as phosphorus sources for alfalfa.  
    Use of straight phosphate sources (0-46-0) over ammonium phosphate is preferred to minimize weed competition.  
    However, the availability of straight phosphates is very limited, and the use of ammonium phosphates (18-46-0, 10-34-0) as phosphate sources for alfalfa is perfectly acceptable.
    Potassium removal of alfalfa is quite high when compared with grain crops.  Soil testing is essential in determining potassium need and rate of application.  
    Application times and methods are similar to those for phosphorus and in most cases these nutrients are applied together.  
    Potassium fertilizer sources are considered equal for supplying potassium.  It also appears that applying potassium-chloride (0-0-60) each year may help to extend stand longevity.
    Weeds generally are not a serious problem the first few years after the successful establishment of a well-fertilized, insect-free alfalfa stand.  
    As the alfalfa stand ages, however, the population often thins, and weeds begin to invade open areas.  
    Both summer and winter annual weeds can be a problem.  Use of herbicides can help improve the quality of a thin, weedy stand of alfalfa but it will not rejuvenate the crop.
    Herbicides used in established alfalfa can be divided into two groups, depending on application and timing.  At this time we will focus on dormant-season treatments which are applied during the winter when the alfalfa is not actively growing.  
    The other group is postemergence herbicides which are applied during the growing season.
    Page 2 of 2 - There are several dormant-season treatments available that will control winter annual weeds such as cheatgrass and mustards, as well as provide some residual weed control.  These treatments can be applied to established alfalfa any time after the alfalfa ceases growth in the fall until it resumes active growth in the spring.  Residual activity depends on the herbicide, rate of application and precipitation.
    Dormant-season treatments applied after regrowth occurs in the spring may cause unacceptable crop injury.  
    Rotation to other crops is restricted for up to 2 years following application of some herbicides.  Be sure to read pesticide labels carefully.
    Although the first cutting of alfalfa for 2013 is still several months down the road, it’s not too early to start managing for a good crop.  
    Proper fertilization and timely weed control are two areas we can manage now to help Mother Nature produce us a successful alfalfa crop next year.
    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 by calling (620) 784-5337 or by email at rkmartin@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.
     
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