Do crops' responses to sulfur vary with its forms?

Abstract

The most common formsof S fertilizers in the northern Great Plains are ammonium sulfate (AS), ammonium thiosulfate (ATS), and elemental S (ES). Among these, AS is preferred over the others because of its readily available SO42– form, and it can be blended with other dry fertilizer granules, but SO42– is prone to leaching. Recently, fertilizer industries introduced micronized (<100 μm) S (MS) fertilizer formulations to hope that the smaller elemental S particles would increase the rate of S oxidation. Across the Red River Valley of North Dakota and Minnesota, field trials were conducted to compare the response of corn (Zea mays L.), spring wheat (Triticum aestivum L.), and sugar beet (Beta vulgaris L.) to the application of different forms of S (AS, ATS, mono ammonium phosphate or MAP-10S [5% ES + 5% AS], MAP + MS, AS + MS, muriate of potash [MOP] + MS, urea ammonium nitrate [UAN] + MS). Spring wheat only had a significant positive response to S forms, with ATS having the highest grain yield in 2019, significantly higher than AS and AS + MS. In 2020, UAN + MS had the highest grain yield, only higher than the control. Corn and sugar beet did not respond to addition of or to S forms. Corn, sugar beet, and spring wheat yields were indifferent to supply and forms of S in the Red River Valley.