What has changed? |
Why the change? |
Soil Sampling |
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Sample every 3 to 4 years in a consistent way as the foundation for an adaptive nutrient management program. |
No changes. |
Soil pH and Lime Recommendations |
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Michigan and Indiana liming recommendations are consistent, Ohio recommendations are different. |
States label and regulate liming materials differently. |
Nitrogen Fertilizer Recommendations |
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Corn N recommendations are now based on economic model to maximize profitability. |
Fluctuating grain and fertilizer prices necessitate a focus on economics in addition to yield. |
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Wheat N recommendations have been updated. |
They are calibrated with recent field trials with modern varieties. |
Phosphorus and Potassium Recommendations |
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Management framework drops drawdown range, makes build-up recommended but not required. |
These recommendations are simplified to provide farmers with greater flexibility to manage nutrients profitably. |
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Default soil test P and K levels now based on Mehlich-3. |
These recommendations are consistent with current soil test extracts. |
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P critical level 20 ppm for corn and soybean, 30 ppm for wheat and alfalfa (Mehlich-3 P). |
This update is based on extensive field trials over past decade. |
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K critical levels are 100 ppm for sandy soils, 120 ppm silt and clay soils (Mehlich-3 K, all crops). |
This update is based on extensive field trials over past decade. |
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Grain nutrient removal rates per bushel of yield have decreased. |
Crops are yielding more but grain nutrient concentrations have decreased. |
Calcium, magnesium, sulfur recommendations |
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Liming supplies sufficient Ca & Mg; S deficiencies remain infrequent but are increasing |
No changes |
Micronutrients |
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Most soils supply sufficient micronutrients; diagnostic tools are limited |
No changes |
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 the main points of the document but lacking comprehensive detail. For complete information, please see the full version which is available from The Ohio State University Extension Publications Store.