3/27/2018 - By Harrell's

??There is some skepticism within the turfgrass industry about the need and role of potassium (K⁺) in turfgrass maintenance. Currently, there are no conclusive research data that supports these initiatives; however, the skepticism has raised many questions from golf course superintendents as to whether they should apply potassium or not. The information below is a “basic” review of potassium that may help you better understand what it does in plants and whether you should consider its use in your turfgrass fertility plan.

What are the characteristics of Potassium (K⁺)?

• K⁺ is highly water soluble
• It has a low order of binding strength to cation exchange sites (CEC)
• Na⁺ = K⁺ < NH₄ ⁺ < Mg⁺² < Ca⁺² < H⁺ < Al⁺³
• K⁺ is very susceptible to leaching, especially in coarse textured soils

How does K⁺ increase turfgrass plant tolerance to stresses?

• As K⁺ concentration increases in plant cells, their cell walls thicken
• Plant cell water content then decreases and cells become more turgid
• Turgid cells are more tolerant of stress and pests

What is the role of K⁺ in turfgrass plants?

• Considered the “plant health” nutrient
• K⁺ is an enzyme that is essential for production of proteins and sugars
• Improves plant tolerance to stresses such as cold, heat, and traffic
• Improves plant tolerance to diseases
• Involved in the regulation of stomatal opening and closing
• Improves plant water use efficiency

How does K⁺ increase turfgrass plant tolerance to stresses?

• As K⁺ concentration increases in plant cells, their cell walls thicken
• Plant cell water content then decreases and cells become more turgid
• Turgid cells are more tolerant of stress and pests

What are the sources of K⁺ used in fertilizers?

How much K⁺ should I apply?

• Normally, K⁺ use rates are based on soil testing recommendations
• K⁺ is often present in the soil at high levels but may not be available
• Only small amounts of K may be in the K⁺ form available for plant uptake
• There is no correlation to soil K⁺ levels and optimum plant response
• Tissue testing is best indicator of K⁺ levels, but environmental factors complicate correlating soil and tissue K⁺ levels
• Soil microorganisms and clipping removal can deplete K⁺ levels
• When available, plants will absorb much more K⁺ than required (called luxury consumption)
• As a general rule, K⁺ requirements range from 50 to 200% of the amount of nitrogen applied depending on turfgrass culture and use intensity
• More K⁺ should be applied as lower nitrogen rates are utilized and use intensity increases

What are the leaching characteristics of K⁺ fertilizer sources?

Potassium Sources

What are the benefits of using Polyon K⁺ fertilizer sources?

• Slow release supply of K⁺ for 14 to 52 weeks depending on specific Polyon product
• Minimal leaching loss of K⁺
• Most economical source of K⁺ on a per week of use basis
• What are some Polyon K⁺ product use programs?
• Surface broadcast applications as a blend component in granular fertilizers
• Surface broadcast applications after quad or needle tine aerification
• Apply to open core aerification holes prior to topdressing

To learn more about the benefits of Potassium, please contact your Harrell's representative!