The sulfur (S) is an element essentially plastic and is found in plants as a constituent of some important amino acids (cystine, cysteine, methionine) which in turn make up proteins. Enters also be part of other important components such as co-enzymes and vitamins. Sulfur is absorbed only in the anionic form and is present in the soil as organic and inorganic. The inorganic forms of the element in the soil are represented largely by sulfates and sulfides. The quantity of sulphates present also has a considerable influence on the pH of the soil. The organic form, an essential component for bacterial flora, consists of plant debris and plays an important role, since in many cases it is the most important source for the supply of plants. The importance of sulfur is then linked to both the protein synthesis is to photosynthesis.