AGRONOMIC NEWS ITEMS
From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335
Fall 1996, No. 4
POTASSIUM: A KEY TO GOOD TURF QUALITY
Potassium is second only to nitrogen in the amounts required by turfgrass plants. Soil potassium can be quickly depleted under turfgrass. Therefore, regular applications of potassium fertilizer are usually necessary to achieve optimum performance. In some cases, the recommended potash rate may be as much as twice that of nitrogen.
Potassium is involved in several vital physiological functions in the turfgrass plant, even though it is not a constituent in plant components such as proteins, fats, and cellulose. Some of the functions in which potassium is involved include the regulation of internal water, photosynthesis and respiration, enzyme activation, and metabolism of carbohydrates, protein, and oil.
Proper potassium fertilization of turfgrass has been shown to be associated with several key benefits.
Increased disease resistance. The incidence of diseases such as brown patch and dollar spot may be reduced by potassium fertilization. The increased disease susceptibility with low potassium levels is associated with thin, easily damaged cell walls and an accumulation of nitrogen and carbohydrates in the plant. This provides a favorable media for pathogen activity.
Increased cold and heat tolerance. The winterhardiness of warm season grasses such as common bermudagrass and the hybrid bermudagrasses is improved with increases in potassium levels. The heat tolerance of cool season grasses such as Kentucky bluegrass and creeping bentgrass is associated with adequate levels of potassium.
Improved overall ability to endure stressful conditions. Satisfactory levels of potassium cause an increase in leaf turgor pressure (decrease in succulence), thicker cell walls, and increased vigor. These attributes yield turfgrass that is more likely to endure stressful conditions such as drought and excessive traffic.
The recent trend in highly trafficked turf areas has been toward more sandy growing media to combat soil compaction. The use of sand to modify or replace existing soil may dramatically reduce the nutrient retention capacity of the turfgrass root zone. Potassium fertilization is especially important under these conditions.
Soil testing should be used to determine turfgrass fertilization needs. Factors such as the degree of traffic should also be considered when designing a turfgrass fertility program.
From the golf course superintendent to the homeowner, a turfgrass manager can maintain healthy, resilient, and aesthetically pleasing turf by maintaining a balance among the essential plant nutrients.
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