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Agricultural Best Management Practices

Fertilizer Rate & Expected Yield

How much nitrogen fertilizer should a farmer apply to a corn crop? Corn’s total nitrogen requirement is related to yield expectation. Establishing a realistic yield expectation is important to good nutrient management and preventing nitrate contamination of groundwater. To calculate a realistic expected yield, the University of Nebraska recommends this method:

1. Use the average of the five most recent crop yields.
2. Add 5 percent.
3. Omit any unusually bad years (hail damage, etc.)

This figure can be plugged into a University of Nebraska formula to calculate the amount of nitrogen fertilizer needed: Fertilizer (lbs/A) = 35 + (1.2 x Expected Yield) minus credits for other nitrogen available to crop (from irrigation water, soil, organic matter, manure, and legumes) To learn more about calculating nitrogen credits for irrigation water, soil, manure and legumes, see the information elsewhere on this Web site. But as this simplified version of the formula shows, it is essential to start with a realistic expected yield.

Additional Information

For more details and information, contact the Cooperative Extension or USDA Natural Resources Conservation Service.

Online Resources

• Yield Gaps and Input-Use Efficiency of High-Yield Irrigated Corn in Nebraska (Extension NebGuide)
• Fertilizer Suggestions for Corn (Extension NebGuide)
• University of Nebraska IANR Extension Information

More Agricultural Best Management Practices

• Nitrogen Credits for Manure and Legume Crops
• Nitrogen Credits for Soil and Water