Fertilizers
Potassium Fertilizers
Elemental potassium is not found in a pure state in nature because of its high reactivity. Potash deposits occur as beds of solid salts beneath the earth's surface and brines in dying lakes and seas. The term “potash” is a general term that is often used to refer to a variety of potassium fertilizers or sometimes more specifically to potassium chloride, the most widely used potassium fertilizer.
Potassium Chloride
Potassium chloride is the most widely applied potassium fertilizer because of its relatively low cost and because it includes more potassium than most other sources. It is very soluble and readily available to plants. Granular forms of this material can be soil-applied, alone, or in dry bulk blends. Farmers spread potassium chloride onto the soil surface prior to tillage and planting.
Potassium Sulfate
Potassium sulfate is an excellent source of nutrition for plants. Growers frequently use potassium sulfate for crops where additional chloride—from more common potassium chloride fertilizer—is undesirable. The partial salt index of potassium sulfate is lower than in some other common potassium fertilizers, so less total salinity is added per unit of potassium.
Potassium Nitrate
Potassium nitrate is a soluble source of two major essential plant nutrients. Potassium nitrate contains a relatively high proportion of potassium, with a nitrogen to potassium ratio of approximately one to three. In such soils, all of the nitrogen is immediately available for plant uptake as nitrate, requiring no additional microbial action and soil transformation. It’s commonly used as a fertilizer for high-value crops that benefit from nitrate (NO₃¯) nutrition and a source of potassium (K⁺).
Potassium Thiosulfate
Potassium thiosulfate (KTS) is a neutral to basic, clear liquid solution that can be applied by drip, sprinkler, foliar, or flood irrigation. When used as a foliar fertilizer, KTS should first be diluted with water before applying. KTS has proven to be a great addition to nitrogen and phosphorus starters, because it supplies both potassium and sulfur—nutrients that are often in short supply in cold soils where root growth is limited.
Potassium-Magnesium Sulfate
Potassium-magnesium sulfate, also referred to as langbeinite, is a double salt of potassium and magnesium sulfate. It is commonly used as a dry granular source of potassium, magnesium, and sulfur. Instead, application rate may be based on the need for magnesium, sulfur, or both. Potassium-magnesium sulfate is water soluble, but dissolves slower than some other common potassium fertilizers because its particles are denser than other potassium sources. Therefore, it’s unsuitable for dissolving and applying through irrigation systems unless its finely ground.
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