Assessing sulfur fertilizer response in Ontario's corn, soybean, and winter wheat crops

Abstract

Reduced sulfur deposition levels and increasing crop yields are causing sulfur nutrition concerns for Ontario corn, soybean, and winter wheat crops. Randomized complete block field trials were completed at 28 southern Ontario site-years in 2018 and 2019 to determine the incidence and extent of grain yield response to sulfur fertilization in these species. Sulfur was spring applied as a sulfate or thiosulfate fertilizer source. Corn and winter wheat displayed significant sulfur-induced yield increases at two of five and three of eight site-years, respectively, with soybean providing no definitive response across 15 experiments. Significant profitable response was realized at one corn and one winter wheat trial. However, economic analyses averaged across sites did not show significant profit from sulfur for any of the three crops. Ontario-specific diagnostic tools are needed to predict corn, soybean, and winter wheat field sites that will deliver profitable response to sulfur fertilization within a given season.