Bremer, E., Pauly, D, Strydhorst, S. M. and McKenzie, R. H.. 2021. Can. J. Soil Sci.
Elemental sulphur (ES) fertilizers have high S content, but may not be effective in the year of application due to the time required to oxidize. Rapid oxidation may be possible if the ES has a large surface area in contact with the soil. We evaluated the efficacy of Sulgro 70, a micronized ES fertilizer that is sprayed onto the soil surface, in eight field trials in southern and central Alberta over a two-year period. Under dry conditions in southern Alberta, the relative efficacy of Sulgro 70 to increase S supply to ion-exchange membranes was 22% during the first four-week period after seeding and 53% during the second four-week period after seeding, compared to ammonium sulphate (AS) sprayed on the soil surface. Under wetter conditions in central Alberta, the relative efficacy of Sulgro 70 to increase S supply was variable (51 to 201%) during the first four-week period after seeding and 56% during the second four-week period after seeding. Based on increases in biomass S concentration in three trials where the unfertilized control had low S concentration (<3 g S kg 1), the relative efficacy of Sulgro 70 was 34%. Canola seed yield was not increased by application of AS nor Sulgro 70 in any of the trials. Sulgro 70 sprayed on the soil surface oxidized appreciably during the first eight weeks after seeding and, with suitable management, has the potential to meet canola S requirements in the year of application.
