Potassium Sulfate Fertilizer Analysis

Plant Needs

• Potassium and sulfur play important roles in plant development. The only mineral that plants absorb more of than potassium is nitrogen. Potassium helps build proteins, is used during photosynthesis, boosts disease resistance and improves fruit quality and production. Sulfur helps in the formation of chlorophyll, an essential component of photosynthesis. Additionally, sulfur improves root growth, seed production and cold resistance and promotes the production of proteins, enzymes and vitamins.

Production

• Potassium sulfate occurs naturally in mineral salt deposits. These deposits are mined and refined. Electrolysis separates potassium chloride and sulfur-bearing salts in the deposits. The potassium and sulfur ions are then joined in a controlled laboratory setting. Potassium sulfate can also be synthesized as the result of a reaction between potassium chloride and sulfuric acid or harvested from the solar evaporation of natural brines from saline lake beds.

Physical Characteristics

• Potassium sulfate is a colorless or white, odorless, stable crystal, granule or powder that has a bitter, salty taste. It has a neutral pH level at or near 7.0. It is soluble in water but not in alcohol or most organic solvents.

Chemical Properties

• Also known as sulfate of potash, the chemical composition of potassium sulfate (K2SO4) contains two atoms of potassium, one atom of sulfur and four atoms of oxygen. Potassium sulfate fertilizer is 50 percent potassium and approximately 17 percent sulfur.

Usability

• Approximately 90 to 98 percent of potassium in the soil is not usable by plants. Over time, this naturally occurring potassium breaks down into plant-usable potassium. Unfortunately, the process moves too slowly to replenish the potassium on farm fields and in gardens. Potassium sulfate is highly soluble in water and is a readily available source of potassium for plants.

Benefits

• Although potassium sulfate provides a significant amount of potassium and a useful trace amount of sulfur, potassium chloride is more commonly used in fertilizers instead of more costly potassium sulfate. However, potassium sulfate is beneficial on crops that are sensitive to chloride such as potatoes, lettuce and tobacco. In areas with a heavy concentration of chloride in the water, chloride accumulates to harmful levels in the soil, making potassium sulfate the safer fertilizer choice over potassium chloride.