Be More Than Oh-K: How To Manage Your Field’s Potassium Levels

Potassium (K) is a fascinating macronutrient. In corn, it sets the stage for a healthy and vigorous plant that produces a beautiful ear. 

Even though K is mobile in plants and helps deliver water and other nutrients throughout the plant, it is immobile in soil. This means it needs to be where the roots can reach it. 

For this reason, you want to treat your field’s K supply like your gas tank, says Phil Krieg, Syngenta agronomic service representative.

“If you let it get all the way down to empty, it costs you a lot to fill it back up,” he says. “Whereas, if you fill that gas tank somewhere between half full and full, you have that nice even supply of fuel. If I can start a plant off with a good rich supply of K, it’s going to help it get through stressful times during the season.”

BACK TO BASICS

Corn receives its K needs through its roots, says Krieg: “Uptake is caused by the root intercepting the K, not K moving to the root.”

For this reason, you want to be proactive with your applications, says Daniel Kaiser, University of Minnesota Extension nutrient management specialist. “You don’t want to be reactionary with K,” he says. “It’s better off to apply ahead of planting so plants can constantly feed off it in the growing season. There has been a lot of talk about foliar applications of K, but it has to go through the roots.”

Kaiser and Krieg both recommend testing your soil to see if you are in the optimum range of K, which can depend on your soil type and location. Some regions just naturally have higher K rates in their soil.

“People tend to prioritize P instead of K, but they are hurt by underapplying K,” Kaiser adds. “We have seen a corn yield difference of 60 bu. to 80 bu. when plants suffer from severe stunting due to a deficiency of K.”   

Sara Schafer uses her Missouri farm roots to cover crop management, business topics, farmland and more.