Yara PA182GU12 Ammonium Sulfate STD Grade 21-0-0 50 lbs, white, free flowing granular ammoniacal nitrogen 21% chemically compounded with sulfate sulfur 24%. Ammonium sulfate is ideal for blending or direct application. Coarse, standard, compacted and feed grades are also available. Ammonium sulfate is the preferred nitrogen source for rice, wheat and pastures in sulfur deficient areas and in alkaline row crop areas.