Ammonium sulfate is great source of nitrogen with the acidifying addition of sulfur. Use on alkaline soils and soils with higher pH. Use on trees, shrubs, flowers and vegetables. For a 4 lb. bag apply 3/4 lb. per 100 sq. ft. 20 lb. bag on lawns apply 1/2 lb. per 100 sq. ft. or 5 lbs. per 1,000 sq. ft. 16 lb. bag will cover 5,000 sq. ft water generously after application. This is the preferred fertilizer of blueberries, providing the form of nitrogen that they can use.