Quick reference tables, rounded to the nearest 5 pounds, are provided for corn, soybean, wheat, corn silage, and alfalfa for potassium below. Potassium recommendations differ for sandy soil (CEC <5 meq/100g) and loam and clay soils (CEC >6 meq/ 100g). The tables use CECs of 5 meq/100g or less for sandy soils and 15 meq/100g for loam and clay soils. For Michigan, subtract 20 lb K2O/ acre from the values listed in these tables. Consistent with the original recommendations, these forage crop K recommendations differ from grain crops when soils are above the critical level.
Note the equations and quick tables provide recommendations for pounds of K2O per acre, not pounds of fertilizer per acre. Final fertilizer recommended rates in pounds of fertilizer per acre can be calculated by dividing the provided nutrient recommendation by the percent concentration of that nutrient in the fertilizer. For example, potash fertilizer (potassium chloride) is often 0-0-60, or 60% K2O. A recommendation of 60 lbs of K2O per acre would equate to 100 lbs of KCl per acre. (See the calculation.)
Phosphorus Fertilizer Recommendations
Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa
Executive Summary | Soil Sampling, Handling, and Testing | Soil pH and Lime Recommendations | Nitrogen | Phosphorus and Potassium | Calcium, Magnesium, and Sulfur | Micronutrients | Additional Resources | Authors and Acknowledgements
This website provides a summarized version of the Tri-State Fertilizer Recommendations, reporting only the main points of the document, but lacking comprehensive detail. For complete information, please see the full version which we anticipate being available soon from The Ohio State University Extension Publications Store (extensionpubs.osu.edu/crops/)