From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335

Winter 1997, No. 4


Potassium, just like nitrogen and phosphorus, is essential for developing corn's genetic yield potential. Plant physiologists have set the yield potential well in excess of 500 bushels of grain per acre. Yet, the national average for all U.S. corn producers has not reached one third of that potential. Some yield can be lost due to disease, crop injury by pests, competition by weeds, stress from inadequate moisture or high temperature, timeliness of operations, or perhaps due to inadequate nutrition. Potassium nutrition could be one of those factors in need of attention for corn yield improvement.

    Corn must absorb its potassium from soil reserves and/or from applied fertilizer potassium sources. Regardless of source, a corn crop yielding in the 180 bushel per acre range will require nearly 240 pounds of K2O to produce the roots, stems, leaves and grain. The nutrient reservoir of many soils is inadequate to supply the total potassium needs of high yielding corn, especially during the critical peak demand period just prior to silking.

    The functions of potassium in corn growth are well known. Research by universities and private industry scientists identify why potassium is a vital part of a balanced fertilization program for corn.

    Effective and efficient use of nitrogen. Potassium teams with nitrogen and sulfur to produce protein essential for plant growth. It helps to improve protein level and quality of corn silage for optimum feed value and forage digestibility by livestock. Environmentally, it helps put more of the available nitrogen into the plant where it belongs.

    Optimum rate of photosynthesis. Potassium, nitrogen, phosphorus and magnesium are team members in this process of converting sunlight, water, and carbon dioxide into sugars and forms of stored energy for plant growth. Potassium helps to regulate the supply of carbon dioxide available for photosynthesis, the rate of sugar use by plants during respiration, and more than 60 enzyme systems associated with plant growth.

    Movement of sugars from leaves to grain. Potassium is needed for efficient movement of sugars from leaves, conversion of sugars into starch, and optimum grain fill. A severe shortage of potassium in corn can delay silk emergence, create pollination problems, and result in poorly filled grain on the tip-end of ears.

    Corn...whether grown in Kansas, Illinois or Georgia...performs best when plant nutrition is removed as a yield limiting factor. Potassium is essential for best use of nitrogen, phosphorus and all other production inputs. It helps growers put more high-quality grain in the bin at harvest time, generate optimum profits and do it in an environmentally sound manner.

--- NRU ---

For more information, contact Dr. Noble R. Usherwood, Southeast Director, PPI, 655 Engineering Drive, Suite 110, Norcross, GA 30092-2837. Phone (770) 825-8070. E-mail:
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