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Crop Management Abstract - Crop Management Research

Foliar Potassium Fertilizer Sources Affect Weed Control in Soybean with Glyphosate


This article in CM

  1. Vol. 6 No. 1
    Accepted: Feb 05, 2007

    * Corresponding author(s): nelsonke@missouri.edu
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  1. Kelly A. Nelson *a and
  2. Peter P. Motavallib
  1. a Division of Plant Sciences, University of Missouri, Novelty 63460; and
    b Department of Soil, Environmental and Atmospheric Sciences, University of Missouri, Columbia 65211


Field research in 2003 and 2004 evaluated soybean injury, weed control, yield response, and cost-effectiveness of foliar-applied, commercially-available K fertilizers with glyphosate. Fertilizer sources were applied at the highest soluble rate for dry formulations or were used as the carrier with glyphosate. All K-fertilizer sources had less than 10% injury 7 and 14 days after treatment (DAT) except 0-0-30-0 (%N-%P2O5-%K2O-%S). Tank mixtures of 0-0-62-0, 14-0-46-0, 0-0-50-17, and 3-18-18-0 with glyphosate controlled common ragweed, common lambsquarters, common waterhemp, and giant foxtail greater than 85% and had grain yields similar to glyphosate plus diammonium sulfate (DAS). Gross margins when glyphosate was tank-mixed with 0-0-62-0, 14-0-46-0, and 0-0-50-17 ranged from $290 to 300/acrewhich were similar to glyphosate plus DAS. This research demonstrated that several K fertilizer sources may be combined with glyphosate for cost-effective foliar fertilizer applications while minimizing crop injury and maintaining weed control.

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