In-season Potassium and Nitrogen Applications Based on Crop Demand Curve, Soil and Tissue Sampling

Kevin Poppel

As an essential nutrient potassium (K) plays a critical role in corn plant development and chemical processes. As a result of the number of roles it plays in the plant, potassium uptake and utilization often interacts with the availability and uptake of other nutrients. Potassium specifically affects the uptake of nitrate nitrogen into the plant. According to research done by the International Plant Nutrition Institute, higher yields and nitrogen utilization is improved with adequate potassium levels. There is also greater yield response to nitrogen applications when K is sufficient as well as improved crop response to K when nitrogen is sufficient. This interaction is also observed over years of tissue sampling through the entire Central Farm Service territory. Also shown by the graph below from 2015-2017 a significant number of those samples are showing deficient or responsive nutrient concentrations within the plant of both potassium and nitrogen. In order to maximize yield potential a critical balance between the two nutrients must be achieved.

An improvement in nitrogen use efficiency has been observed by making split nitrogen applications that closely follow the nitrogen demand curve for corn. The goal for the improvement is also to maintain maximum yield potential. Since potassium and nitrogen are both essential nutrients to the corn plant and yield potential and are so closely correlated an improvement in potassium efficiency would likely be observed if potassium was applied more closely to match the nutrient demand curve. By identifying a critical balance between these nutrients, the goal is to maximize nutrient efficiency without sacrificing yield. Based on previous nutrient research theories a yield advantage is possible if the correct ratio is achieved.