Sulphur fertilizer and tillage management of canola and wheat in western Canada

Abstract

A 3-yr field study in Manitoba, Saskatchewan and Alberta evaluated immediate and residual effects of source, timing and placement of sulphur fertilizers on canola (Brassica napus L.) and wheat (Triticum aestivum L.) under conventional (CT) and reduced tillage (RT). Sulphur fertilization did not increase wheat yield, even when soil sulphate was low. Ammonium sulphate (AS) and ammonium thiosulphate (ATS) increased canola yield in 2 of 3 yr at the Saskatchewan site while elemental S and Tiger 90™ did not. Residual S from AS and ATS increased canola yield on S-deficient soils in the second and third crops after application. Canola yield on the S-deficient soil was lower where broadcast Tiger 90 rather than AS or ATS was applied the previous year, indicating that broadcast Tiger 90 oxidation was insufficient to support canola yield in the second crop year after application. Banding or seed-placing Tiger 90 delayed oxidation further. In the third crop after application, canola yield was similar with broadcast Tiger 90, AS or ATS but was lower with seed-placed or banded Tiger 90 than AS or broadcast Tiger 90. Small particle size and broadcast application of elemental S are needed to hasten oxidation of S to sulphate-S.