Sulfur Deficiencies and Sources.

When I started consulting in 2005, we seldom saw sulfur deficiencies in any crop.  We were even then seeing soil test sulfur levels drop.  We were making recommendations for sulfur, but some customers questioned the need. Now, we see sulfur deficiencies in the spring almost daily.  Many more clients have started to use sulfur.  Commons sources are elemental sulfur, gypsum, or ammonium sulfate.  Some are using the liquid form, ammonium thiosulfate in row.

Topdressing Wheat with Sulfur is a recent article in No-Till Farmer.  
While we do not have lot of wheat in our area, the information on forms of sulfur fertilizer is vvery good.  Click on the Link.