Wheat

• Out of 18 site-years in North Dakota and NW Minnesota, sulfur (S) fertilizer improved wheat yields at 5 out of 19-site years. Sulfur improved yields by 4 to 7 bushels/ac at those five sites.
• Nitrogen fertilizer consistently improved yields. However, when N in soil was too low or too high, sulfur did not significantly affect yields. Sulfur had the most effects on yield when an adequate rate of nitrogen (N) was applied.
• An economic analysis of the wheat results suggested that the range of N fertilizer rates that would result in a profit is very narrow; implying that very careful N management planning is key to ensuring optimum fertilizer use, and minimizing profit loss.

Corn

• Out of 12 site years (all loam soils), S significantly improved corn yields by up to 30 bushels in southeast ND (at Forman and Oakes), but had very little impact on yields in the Carrington area. Yields were not affected by sulfur at 7 sites in 2019.
• In site years that were responsive to sulfur, it was estimated based on the nitrogen response yield curve, that the amount of nitrogen required to maximize yields was lowest when 10 lbs of sulfur was applied (Table 1).

Conclusions

• Application of S at 10 lbs/ac produced the highest yields for both wheat and corn, compared to 0 or 20 lbs.
• Even though 10 lbs of S was enough to maximize wheat and corn yields, under conditions of high S leaching (sandy soils) or prolonged wetness, up to 15 lbs may be applied.
• Including S in fertilizer planning to avoid S deficiency is more efficient and less costly than correcting S deficiency.
• Application of ammonium sulfate and other sulfate forms of fertilizers (potassium thiosulfate, gypsum, etc.) are recommended over straight (elemental) sulfur.

Jasper M. Teboh, Ph. D.
Jasper.Teboh@ndsu.edu
Soil Scientist