Michigan State University Extension
Soils & Soil Management - Fertilizer - 06109709
07/10/97
Potato Fertilizer Recommendations Extension Bulletin E-2220, April 1990
Maurice L. Vitosh Extension Soil Specialist Department of Crop and Soil Sciences
Sulfur
Though sulfur (S) is an essential nutrient, field studies with several responsive crops on many sites throughout Michigan have not shown any benefit from sulfur applications. Potatoes are less responsive to sulfur than many other crops. (See the discussion above on ammonium sulfate under the section on N fertilizer sources with regard to its use in reducing potato scab disease.) Soil Testing
Nutrient Management to Protect Water Quality Extension Bulletin WQ-25, January 1996
Maurice L. Vitosh and Lee W. Jacobs Extension Soil Specialists Department of Crop and Soil Sciences Michigan State University
Soil testing is one of the best tools we have for obtaining an inventory of the nutrients that the soil can supply. One of the keys to a good soil testing program is proper soil sampling. MSU Extension bulletins E-498, "Sampling Soils for Fertilizer and Lime Recommendations," and E-2567, "Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat and Alfalfa," available from your county Extension office, give instructions for obtaining a good representative soil sample. Fertilizer, manure additions and nutrient removal by crops will alter the soil test, so each field should be tested every two to three years. For high value crops or fields where large amounts of fertilizer are added, retesting every year is desirable. Once we have determined what the soil can supply, we can better determine whether the crop needs supplemental nutrients. Fertilizer recommendations based on soil tests frequently vary between soil testing laboratories. Although some commercial laboratories recommend more fertilizer than Michigan State University does, numerous studies have shown that MSU recommendations are adequate and economical.