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Timing of K application for corn and soybean production

Study author(s): Daniel Kaiser, University of Minnesota
Years of study: 2022
Location(s): Crookston MN, Rosemount MN, Lamberton MN, Rochester, MN

Important: for the complete report, including all tables and figures, please download using the links to the right.

Read Full 2023 Report


  • Potassium application rate and timing had inconsistent impacts on corn leaf and soybean trifoliate K concentration. When significant, leaf K concentration tended to increase linearly with increasing K application rate.
  • Leaf Cl concentration was increased greater with spring application of potash fertilizer. Fall application either did not increase or only slightly increased Cl concentration. Results though 2022 show that increased Cl concentration in the leaf tissue did not result in decreased corn or soybean yield.
  • Corn grain yield was increased with K application at one corn and two soybean locations. The 2022 growing season is the first of a multi-year study. Timing of K application seldom, if ever, affected corn or soybean grain yield through the first year of the study.
  • Seed K concentration and K removal with harvested corn or soybean grain were inconsistently impacted by K application rate and timing.
  • Soybean seed protein and oil concentration were not impacted by K application rate or timing.
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