Agronomists from Ohio State University’s College of Food, Agricultural, and Environmental Sciences have updated a fertility recommendation calculator designed to provide major field crop growers with guidance on fertilizer application rates and costs.

The updated tool offers users calculations based on tri-state (Indiana, Michigan and Ohio) fertilizer recommendations for corn, soybeans, wheat only, wheat for grain and straw, corn silage, and alfalfa, said Greg LaBarge, an Ohio State University Extension field specialist.

Developed by agronomists, the calculator is in the form of a spreadsheet that is easy to use and designed to help growers get the most accurate results, LaBarge said.

“It’s one way to get at what that fertility number needs to be, making sure it’s not too high or too low,” he said. “The spreadsheet has been updated to prove more functionality using feedback from growers who’ve used previous versions of the calculator.”

Some of the new functions the tool offers include:

• Phosphorus soil test results using Bray P1 or Mehlich III that can be entered directly without conversion.
• Phosphorus and potassium soil tests that can be reported in units of pounds per acre or part per million.
• A lime recommendation sheet that provides lime need based on Effective Neutralizing Power of the liming source and calculates the cost of the product and application.
• A fertilizer recommendation sheet that calculates dry fertilizer need and cost on a per-acre and total-field basis.

The spreadsheet allows users to select the phosphorus test and unit and enter their crops, yield goals and soil test results to calculate the soil fertilizer application rates and costs recommendations. The calculator can be downloaded at http://agcrops.osu.edu/specialists/fertility/fertility-fact-sheets-and-bulletins/TriStateFertCalcV2013-4.xlsm.