Evaluation of Critical Potassium Levels in Minnesota Soils


Start Date: 2011

Principal Investigator: Daniel Kaiser

Organization: University of Minnesota, Department of Soil, Water and Climate

Status: Complete

Background Information:

According to current recommendations, response to applied potassium (K) is likely when soils test lower than 160 ppm. Simple strip trials can be used to correlate crop response to soil test values. Paired strips, with or without K fertilizer, can be used to determine relative crop yields, which can be correlated to soil test values.


Three strip trials consisting of about 2 acres were planted each year, and soil samples will be collected from the 0–6-inch and 6–12-inch depths every 40 feet. Yield data will be collected at the same intervals and correlated with the soil data. The data will be compiled to determine the soil test level above which yield response to K is not expected. This information will be used to update the current recommendations.

Key Finding:

©2017 Agricultural Fertilizer Research and Education Council of Minnesota