Sulfur and nitrogen management in wheat

By Greg LaBarge

Sulfur (S) and nitrogen (N) cycles in the soil are very similar. Plant uptake sources for both nutrients come from the soil cycling of organic matter, atmospheric deposition, plant residues, manures, and fertilizer additions. Losses of both nutrients occur through leaching, volatilization, and bacterial transformations that result in gaseous sulfur or nitrogen forms. These characteristics impact S and N management in wheat.

For example, mineralization is an important S source for row crop production. Mineralization can provide 3-5 pounds of S per percent organic matter. But mineralization is soil temperature-driven. Thus, cool spring conditions slow the S and N release process. Total OM is also a factor. Sulfur yield response probability increases at lower soil OM (1-2%).

Wheat crop needs differ between S and N. S removal rates in an 80-bushel wheat crop are 6 pounds (12 pounds of SO4 sulfate), while N removal is 77 pounds. If you add a fertilizer S source to wheat, keep these relationships in mind.… Continue reading