Sulfur deficiency problems exist in northeast Iowa alfalfa production fields. The majority of S deficiency problems occur in areas within fields, not entire fields. However, this non-uniformity can still account for large economic losses on a field scale. Most of the soils involved are lower organic matter, side-slope position, silt loam soils. Lighter textured loam soils have also responded to S fertilizer in these trials. Wapsie loam in 2006, Winnshiek loam and Saude loam in 2005. Problems with S deficiency are not occurring on heavily manured fields. Currently, if a S deficiency is found (i.e. through plant analysis or field trial), the amount of S fertilizer recommended is usually 20 to 30 pounds S/acre. Where deficiencies occurred in the 2006 trials, the first 15 pounds of S/acre gave the largest incremental increase in yield, but the next 15 pounds of S/acre was still profitable in most trials. Also, S fertilizers do not need to be applied each year as alfalfa will respond to S applied in a prior year. Therefore, it is possible to apply the crop needs for multiple years in one application. That rate will be more than is needed for just one year.