Resources for determining fertilizer rate

4R Nutrient Stewardship is an industry driven concept of looking at soil nutrient application. The program utilizes a science-based approach to nutrient use in crop production. The program has three goals that match to our goals in Ohio Agriculture.

  • Increase crop production & improve profitability
  • Minimize nutrient loss & maintain soil fertility
  • Ensure sustainable agriculture for generations to come

Due to its common sense approach to define best management on the farm, this concept was quickly adapted in relation water quality concerns in Ohio's waters, when the Directors of Ohio Environmental Protection Agency, Ohio Department of Natural Resources and Ohio Department of Agriculture met with the agricultural and environmental groups in the fall of 2011. From a farm standpoint, it considers economics of nutrient use, returns through harvested yield and incorporates practices to keep nutrients on the field for future crop production rather than leaving the field in water runoff.

The 4R Nutrient Stewardship considers the rate of nutrients needed for the crop, then the characteristics of the nutrient source used to meet that need, as affected by the placement and timing of application. We want to use the right rate, right source, right timing and right placement in nutrient application or 4R Nutrient Stewardship.

Ohio State University Extension has several new resources that are available on our website for determination of rate of nutrients needed. These resources can be found at

Two resources can be used if you have a current soil test in hand to provide a recommendation for phosphorus and potassium. The first is a spreadsheet that will develop recommendations for up to seven fields with up to a three crop rotation. In addition to the nutrients mentioned, a lime recommendation can be generated as well. The beta version of this spreadsheet is found at  If you prefer to use a paper copy, the new factsheet Developing Phosphorus and Potassium Recommendations for Field Crops (AGF-515-12) is available that walks you through using the printed tables from the publication Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat and Alfalfa E-2567.

If looking at soil test reports is new to you, or you are out of practice, the factsheet Interpreting a Soil Test Report (AGF-514-12) points out key parameters to look at on the report. It is available at This factsheet walks you through a soil test report describing desirable ranges and what the numbers mean on your report.

A current soil test is the foundation to develop a fertility program. If you do not have a current soil test (taken in the past three years) a good place to start is with a new soil test. The factsheet Soil Sampling to Develop Nutrient Recommendations (AGF 513-12) is available at This factsheet discusses how to look at a field to get a representative sample, guidelines to taking a sample and sending a sample to the lab. Traditional as well zone and grid sampling schemes are covered. If you are looking for a laboratory to send your collected samples to there is a reference for soil testing labs in and around Ohio at


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