2019 Seminar Series - Dr. John Lauzon


Sulphur fertilization in Ontario

by Dr. John Lauzon, School of Environmental Sciences, University of Guelph

LOCATION: Room 202, Crop Sci
DATE & TIME: Thursday, January 24, 2019 @ 11:00 AM


Sulphur was one of the first fertilizers applied in Ontario. Before 1880 “land plaster” (gypsum) was commonly applied to farm field as a source of sulphur for crop production in Southern Ontario.  Starting in about 1880 single super phosphate started to be applied, which in addition to phosphorous, contains about 14% sulphur. This continued until the 1950’s when ammonium phosphate largely replaced super phosphate as the primary form of phosphorus fertilizer used in Ontario.  Although ammonium phosphate contains no appreciable amount of sulphur, studies at the time reported that sulphur fertilization was no longer required in southern Ontario. The lack of response to sulphur was attributed to sulphur deposition which generally exceeded 30 sulphate ha-1 yr-1. This quantity more than met the crop requirement.  However, starting in the late 1970’s improved environmental protection has been progressively reducing deposition levels to about 8 ha-1 yr-1.  Although this level of deposition is still one of the greatest in North America, it is at a level that crop responses to applied sulphur are more likely.  A number of studies have been conducted in Ontario in the last 15 years to evaluate current crop responses.  In general, alfalfa, canola, and winter wheat were found to respond in about ½ of the trials.  Positive responses to applied sulphur in corn and soybean are more uncommon.  As such, we are attempting to develop a large enough database of trials in Ontario to identify conditions that are likely to result in response to avoid unneeded applications.


John Lauzon has been a soil science professor at, University of Guelph since 2000. Current teaching include the introductory soil science courses and 4th year courses in soil and nutrient management as well as graduate level instruction in soil nitrogen management.  Research interests focus on crop nutrient management strategies to maximize the agronomic use of plant nutrients and minimize losses.