Source: John Grove, research and extension soils specialist; and Edwin Ritchey, extension soils specialist, UK Research and Education Center at Princeton 

To maximize yield and economic return on every acre, begin with a soil test. A current soil test from the University of Kentucky ensures you will receive more accurate fertilizer recommendations, optimized for your crop, field history and production methods.  

University of Kentucky Cooperative Extension Service publication AGR-1, Lime and Nutrient Recommendations, was recently updated for the 2025-2026 crop seasons, and new recommendations are a result of a review of soil fertility research and soil test data collected across the state. It covers nutrient recommendations for grain crops, forages, tobacco and several specialty crops.  

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. All recommendations are made on the assumption that a representative soil sample was taken. If soil sampling procedures are questionable, accurate nutrient and lime rate recommendations for the sampled field or area cannot be assured. Because results can vary between fall and spring sampling, it is better to consistently sample a given field at the same time of the year.  

When sampling untilled fields in the fall, an equal number of cores should be collected from both between and close to the rows. For tilled areas, take soil cores to the depth of primary tillage (plow, chisel plow, big disc, etc.), usually six to eight inches. With pastures, lawns, no-tilled areas and turf, take soil cores to a depth of four inches.  

With changing fertilizer and commodity prices, each production field should be sampled every two years. Annual sampling is preferable for high-value crops or rotations that remove large amounts of soil nutrients, such as alfalfa, tobacco and double-crop silage. Sampling each year after manure application is also recommended.  

Recommended nitrogen additions are made with an expectation of a yield response as measured for that crop under Kentucky soil and weather conditions. Yield responses to phosphate and potash rate recommendations are more likely when soil test levels “very low”, “low” and “low-medium.” When the soil test value is “medium” or higher, associated phosphate or potash rate recommendations are mostly intended to ‘maintain’ sufficient soil phosphorus and potassium availability.  

Field research yield and soil test relationships measured by the Kentucky Agricultural Experiment Station were used to establish the phosphate and potash recommendations contained in AGR-1. Those recommendations 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 the (COUNTY NAME) Extension office for additional information, or view AGR-1 at https://publications.ca.uky.edu/agr-1. 

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