Analysis: 21-0-0. Hi-Yield Ammonium Sulphate is a fast release, quick acting source of nitrogen that supplies rapid growth and greening to all plants in your yard, vegetable garden, or ornamental garden. Ammonium sulfate, sometimes known as Mohr's Salt, is a chemical compound commonly used as a fertilizer. Ammonium sulfate is quite acidic and will lower the pH balance of the soil as well as other sulfate compounds such as aluminium sulfate. Ammonium sulfate contains 21% nitrogen as ammonia and 18% sulfur as sulfate. Ammonium sulfate supplies sulphur to aid in acidifying of soils. Application rate: 3/4 lb. per 100 sq. ft.