The Importance of Sulfur as a Plant Nutrient in World Crop Production

S deficiencies in crop production are increasing because of: (a) the increasing use of S-free fertilizers; (b) the decreasing use of S as a pesticide; and (c) increasing crop yields, which require greater amounts of plant nutrients. Atmospheric supplies of S is an additional factor that should be considered. The functions of S as a plant nutrient are discussed with examples of crop responses resulting from the application of this element. The various sources of fertilizer S are enumerated. The role of S in animal nutrition is briefly considered and the importance of an adequate supply of dietary S for the effective utilization of N by ruminants is pointed out.