The Importance Of Potassium In Forage Systems

eKonomics News Team

Summary of what you'll find

The importance of potassium in forages
Adding potassium to your forage system
Managing potassium in forage systems

Potassium, most often applied as potash (K₂O), is frequently overlooked in pasture systems despite being required in greater amounts than any nutrient other than nitrogen. A recent Progressive Forage article published by Agronomist Mike Howell highlights the critical role potassium plays in supporting forage resilience including root development, winter hardiness, water use, and enzyme activation.

The importance of potassium in forages

Within the plant, potassium supports photosynthesis and aids in the movement of carbohydrates – essential for regrowth after grazing or cutting. It also helps plants manage water stress under drought and better withstand disease.

Without adequate potassium, nitrogen use efficiency is reduced, limiting yield and forage quality. But deficiency is not always easy to detect – because potassium is mobile in the plant, deficiency symptoms typically show up first on older leaves and may include stunted growth and a higher susceptibility to stress.

Adding potassium to your forage system

Monitoring soil test levels can help you better track your need for potassium while helping you avoid deficiency. When levels indicate an application is needed, you have several sources to choose from.

Common potash fertilizers: MOP vs. SOP

The most common sources of potassium in the field are potassium chloride, also referred to as muriate of potash (MOP), and potassium sulfate, also referred to as sulfate of potash (SOP). Once you identify the source that fits your fields, you can decide how to manage it. The two most common approaches include:

A build-and-maintain approach: Soils are fertilized to bring soil test levels up and then monitored and maintained. This is referred to as “feeding the soil.”

A sufficiency approach: Fertilizer decisions are based on crop removal. If you know how much of a given nutrient your crop needs to produce a given yield, then you replace that amount with fertilizer. This can be thought of as “feeding the plant.”

Refer to state level guidelines relating to pasture production and potassium fertilizer applications to dial in application rates and timing.