The ROSI® (Return on Sulfur Investment) calculator is a handy tool that calculates the estimated return a grower could receive by incorporating sulfur into their fertility program each season. Backed by research from The Sulfur Institute and International Plant Nutrition Institute, the ROSI® calculator gives users the flexibility to change many different key market variables by crop and region, such as crop value, nitrogen source price, ammonium sulfate price, and sulfur application rate.