Nutrient rate recommendations have changed to help producers achieve yields that maximize economic return
Nutrient rate recommendations have changed to help producers achieve yields that maximize economic return
Published on August 15, 2025
University of Kentucky extension publication AGR-1, Lime and Nutrient Recommendations, has been updated for the 2025-2026 crops seasons. These new recommendations are a result of a review of soil fertility research and soil test data collected across the state.
Notable changes from previous years will be found in nitrogen rate recommendations for corn and small grains (wheat, rye, barley) and phosphate and potash rate recommendations for corn, small grains and soybean.
Nitrogen rate recommendations for corn are largely influenced by the previous crop, tillage, soil drainage class, presence of a cover crop and N loss inhibitor use. Tables in AGR-1 provide N-rate guidance for previous crop, presence of crop residue, tillage practice and soil drainage class. N-loss inhibitors are also being considered.
The P₂O₅ and K₂O rate recommendations for corn are intended to build and maintain available soil P and K at levels sufficient to ensure P and K nutrition for optimal crop yield with good management and weather while minimizing applications that have a low probability of benefit.
Recommended fall nitrogen application rates for small grains should only provide for good ground cover and stimulate tillering, without excessive fall growth that can encourage spring freeze damage. Seedings following tobacco, soybean, or well-fertilized corn will likely have enough carryover N for fall growth. For optimal fertilizer N efficiency, the total fall application should not exceed 40 lb N/A for seedings in fields with insufficient N carryover. Fall-applied N will be of little benefit where little fall growth is expected.
The lime rate recommendation for small grains and soybean should be used to achieve a target water pH of 6.4. For those double-cropping small grains and soybean, the recommended amounts of P and K fertilizers should be applied in the fall before seeding the small grain.
Please remember that soil testing is the first important step to a sound nutrient management program. To get reliable recommendations, it is important that the submitted soil sample accurately represents the field or area from which it was taken. Analytical results provided on the soil test report form are for the sample submitted, and the listed recommendations are based on those results.
If nutrient recommendations must be made without soil test results, assume low levels of residual nutrients. This approach can result in greater-than-needed fertilizer application and expense, and should only be used when necessary.
Recommended nutrient additions, based on a soil test (except for nitrogen), are only made when a yield response has been measured for that crop under Kentucky soil and weather conditions. The Kentucky Agricultural Experiment Station has conducted many field studies under Kentucky farm conditions to determine primary, secondary or micronutrient needs. Yield and soil test data from these studies serve as guidelines for establishing the recommendations contained in AGR-1. Recommendations in this publication strive to enable each soil/field to supply a sufficient level of available plant nutrients, regardless of seasonal weather and assuming good management practices.
Contact your county Cooperative Extension office for additional information, or view AGR-1 at https://publications.ca.uky.edu/agr-1.
Written by Jennifer Elwell. Source: John Grove, Research and Extension Soils Specialist, and Edwin Ritchey, Extension Soils Specialist, UK Research and Education Center at Princeton
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