The Effect of Sulfur Sources and Rates On Winter Canola Yield and Oil Content.

 Canola (Brassica napus) production in the Southern Great Plains has increased due to its benefits as a winter rotational crop for winter wheat and market value.  However, limited research exists about sulfur (S) requirements of canola in this region.  The objective of this two year study was to evaluate the effect of two forms of S and four application rates of 0, 11.2, 22.4, and 33.6 kg ha^-1 on the yield and oil content of canola seed.  Field experiments were conducted from 2009-2010 and 2010-2011 growing seasons in Lahoma and Perkins, Oklahoma. The two canola cultivars used were Hyclass 154 and DKW 47-15, and the two sources of S were elemental sulfur and ammonium sulfate at both sites. The experiment with 16 treatments was a randomized complete block design with four replications. Surface (0-15cm) and subsurface (15-46cm) soil samples were collected and analyzed for plant available nutrients before planting.  In 2009, the average total soil sulfate-S was 42 kg ha^-1 at Perkins and 46 kg ha^-1 at Lahoma. In 2010, the average at Perkins was 63 kg ha^-1 and 108 kg ha^-1 at Lahoma. The canola seeds were analyzed for oil content using NIR spectrometry.  The average oil content was 47% at Perkins and 42% at Lahoma; and the yields in Perkins were also higher than those in Lahoma for the first year’s trial. However, there were no statistical yield differences between S sources and among S rates for either canola variety during the 2009-2010 growing season most likely due to the high soil sulfate-S. The second year’s yield, oil content, and plant tissue test results will also be presented.