Comparison of Methods for Determination of Sulfur in Fertilizer: Collaborative Study

Abstract Methods with applications for total sulfur (sulfate, elemental sulfur) in dry fertilizers, for total sulfur (sulfate, sulfite, thiosulfate, sulfide) in liquid fertilizers, for total sulfur (elemental sulfur) in sulfur-coated urea and elemental sulfur formulations, and for thiosulfate sulfur in ammonium thiosulfate liquid fertilizer (12-0-0, 26 S), and 7 samples with background and directions were submitted to 12 collaborating laboratories for comparison to official methods 2.160–2.161 and 2.162. The methods studied are simple and rapid, and recover the total sulfur in fertilizers containing high levels of elemental sulfur and thiosulfate sulfur. Method 2.160–2.161 does not recover total sulfur in these products. The first 3 methods have been adopted as official first action, and the present official methods for sulfur, 2.160–2.161 and 2.162, have been repealed, official first action.