What Is Aluminum Potassium Sulfate Used for?

Aluminum potassium sulfate, also called potash alum, kalinite or potassium alum, is a water-soluble material that is rich in potassium. Used as a fertilizer by home gardeners, potassium aluminum sulfate increases the potassium content in soil, a vital nutrient for healthy plant development. Often confused with potash because of its name and function, aluminum potassium sulfate can be added on its own to soil, or used as part of a mixed fertilizer.

Aluminum potassium sulfate increases the potassium content of soil. Because it dissolves easily in water and absorbs moisture when exposed to air, it is ideal for adding directly to soils, as the potassium content becomes immediately available to plants. Aluminum potassium sulfate is considered an inorganic fertilizer, but is safe to use on food products such as garden vegetables.

Potassium, along with nitrogen and phosphorous are key for general plant health and nutrition. While the role of potassium in plant development is not clearly specified, it is believed that it helps with plant establishment, improves water use in plants, is crucial for plant hardiness and helps plants better defend themselves against disease and pests.

A balanced, mixed fertilizer will have equal parts nitrogen, phosphorous and potassium, creating a 20-20-20 ratio, for example. However, if your soil is deficient in only one or two nutrients, you can choose one that skews towards the needed nutrient. For example, a potassium-only fertilizer could have 0-0-50 ratio. To add aluminum potassium sulfate, dilute the fertilizer while wearing gloves. For small volumes, a 1/2 teaspoon mixed with a gallon of water will give you a fertilization rate of 125 parts per million. Mixing a gallon of water with 1 tablespoon fertilizer will give you a fertilization rate of 750 parts per million. Wearing gloves and an eye mask, carefully apply the fertilizer at the base of the plants. Apply aluminum potassium sulfate fertilizer only when plants are already growing or about to grow. Otherwise, because of its high-water solubility, the fertilizer may simply leach away.

Aluminum potassium sulfate is a manufactured chemical produced by combining extracted alumina with potassium sulfate. Potassium sulfate, a salt, is water-soluble, and this property is carried over to aluminum potassium sulfate. "Potash" is commonly used as a general term for all fertilizers rich in potassium. However, true potash is a potassium-rich mineral that can be mined as it occurs naturally.