Historically, sulfur (S) deficiency has not been an issue for crop production in Iowa. Previous research reported sufficient plant available S for crop production on most soil associations. Recent studies across Iowa in corn and soybean production were consistent with results of previous research. The exception was a longstanding suggestion to apply S as commercial fertilizer or livestock manure for alfalfa production on sandy soils. However, over the past decade, alfalfa grown on some silt loam and loam soils in northeast Iowa has exhibited a slowly worsening problem with areas in fields of stunted growth and poor coloration. Recent investigations determined the growth problems were largely due to S deficiency.