Sulphur deficiency in southern Ontario soils; how fertilization will impact canola (Brassica napus L.) and alfalfa (Medicago sativa L.) yield and quality

Abstract

As sulphur (S) deposition has been decreasing across southern Ontario, in recent years S deficiencies in crops with high S demands, such as alfalfa (Medicago sativa L.) and canola (Brassica napus L.), have been becoming more common. To begin establishing S fertilization recommendations for southern Ontario growers, field trials were established in the 2013, 2014 and 2015 growing seasons (2015 only in alfalfa), to assess if these crops showed consistent yield responses to S application. Canola showed variable response, with 4 of 10 trial locations showing significant yield improvement. Alfalfa responded more consistenly, especially in second and third cuts, with 5 of 7 field locations showing significant response to S in at least one cut and/or total yield. Results also showed tissue testing to be a more reliable means of anticipating the need for S application than soil S extraction (by Mehlich III) in both crops.