Michigan State University Extension
Soils & Soil Management - Fertilizer - 06039706
07/10/97
Tri-state Fertilizer Recommendations for Corn, Soybeans, Wheat and Alfalfa Extension Bulletin E-2567 (New), July 1995
M.L. Vitosh, Michigan State University; J.W. Johnson, The Ohio State University; D.B. Mengel, Purdue University; Co-editors
Several tests are available to measure the availability of individual nutrients in the soil. The recommendations made here are based on research conducted using very specific tests, which are identified for each nutrient. Producers and consultants should always be certain their fertilizer recommendations are based on research using the same procedures used to generate their soil test results.
The specific procedures used to test soils in Indiana, Michigan and Ohio are described in NCR Publication 221, 1988, Recommended Chemical Soil Test Procedures for the North Central Region, written by the USDA-sanctioned North Central Regional Committee on Soil Testing and Plant Analysis (NCR-13) and published by the North Dakota Agricultural Experiment Station. Other procedures may yield results incompatible with the recommendations given here.
All soil test data in this publication are reported as parts per million (ppm) rather than pounds per acre (lb./acre). The change to ppm is being made because it more truly represents what is measured in the soil. Soil test values are an index of availability and do not reflect the total amount of available nutrients in soil. The use of lb./acre in the past has also led to some confusion about soil testing and the resulting fertilizer recommendations. Most commercial soil test laboratories are currently reporting soil test values in terms of ppm. To convert ppm to lb./acre, multiply ppm by 2.