Sulfur Fertility of Canola Using Flue-Gas Desulfurization Gypsum.

There are many potential uses of flue-gas desulfurization gypsum (FGDG), including use as a fertilizer.  Canola is a primary crop in North Dakota, which ranks #1 in the nation in its production.  Canola is very sensitive to the concentration of sulfate-S in the soil and yields can be greatly affected by the lack of this nutrient in the root zone.  The objective of this research was to investigate the potential use of FGDG as a fertilizer source for canola and also estimate its potential use for other crops in the northern Great Plains.  A study was conducted in 2008 at the North Dakota State University Research and Extension Center at Langdon to determine canola yield response to FGDG and ammonium sulfate.  Two sites were selected that typically have shown high and medium sulfur responses.  Using RCBD with six replications, total sulfur was applied as ammonium sulfate at 5.6, 8.4, 11.2, 16.8, and 22.4 kg/ha and as FGDG at 11.2, 22.4, 33.6, 44.8, and 112 kg/ha.  Nitrogen was balanced for all plots in the study.  No significant differences in yield (kg/ha) were observed between the ammonium sulfate and gypsum amended plots at the medium-response site but at the low-response site, the FGDG 22.4 kg S/ha was significantly greater than the ammonium sulfate 5.6 and 8.4 kg/ha plots.  The 33.6 and 22.4 kg S/ha FGDG plots produced the greatest yields at the medium- and low-response sites, respectively.  Using a total sulfur application rate of 22 kg/ha for the 0.43 million ha of canola grown in 2007 in North Dakota, 9460 and 45263 Mg of sulfur and FGDG, respectively, could applied per year.