Atmospheric deposition (acid rain and dry deposition) supplied ample sulphur (S) to meet crop needs throughout the last half of the 20th century. Significant efforts to reduce sulphur emissions from industry and diesel fuel began in the 1990’s. As these efforts take effect, free S additions have been greatly reduced. It is a matter of when, not if, we will need to apply sulphur to many of our field crops. The purpose of this trial is to assess response to S, and be proactive in terms of crop needs for applied S as a fertilizer.

Environment Canada records show that in 1990 atmospheric S deposition equated to 30lbs/ac/yr. By 2005 that had dropped to only 15lbs. Canola crops require more than 15 lbs, alfalfa crops have been found S deficient on low organic matter sand soils, and good wheat crops require about 13 lbs S. This trial will determine: if there is response to fertilizer S under current reduced deposition levels: what the S response curve looks like: and our current sulphur requirements.

Methods to predict S response will also be evaluated. Critical values for S soil tests and S tissue tests will be investigated.

Read the entire report here: Winter Wheat Response to Applied Sulphur