Potassium Compounds for Plants

Potassium Compound Sources

• The sources of potassium for plants are few and limited, according to the University of Minnesota Extension. These compounds include potassium nitrate, potassium sulfate, potassium-magnesium sulfate and potassium chloride. The major source of potassium chloride, the most widely used potassium compound in the United States, is obtained from the underground deposits in Saskatchewan and western United States. Potassium-magnesium sulfate is usually used when the soil is also deficient in magnesium and is commonly applied to crops like alfalfa, corn and grains planted in sandy soils. Potassium nitrate and potassium sulfate are relatively more expensive than other compounds and hence are used less.

Functions of Potassium

• Potassium is important for the circulation of nutrients, carbohydrates and water through the plant. It stimulates early growth in the plant by improving water absorption, increases protein levels and improves resistance to infection and pest infestation. The nutrient plays a key role in helping plants deal with environmental stresses, such as high and low temperatures and drought. Potassium regulates the functioning of stomates in the plant that are directly responsible for transpiration and carbon dioxide absorption for photosynthesis.

Optimal Conditions for Potassium Absorption

• Plants growing in well-aerated, moist soil with a pH ranging between slightly acidic and neutral are most capable of absorbing healthy levels of potassium. Warm soils help to elevate the diffusion of the nutrients in the soil that, in turn, help to support potassium absorption through roots. Soils that are excessively moist have reduced oxygen levels that not only affect transpiration in roots but also potassium absorption.

Potassium Deficiency Symptoms

• Plants growing in sandy soils, and those irrigated with water with high levels of sodium, magnesium or calcium are most prone to potassium deficiency. Initial symptoms include browning leaf margins on lower leaves and yellow, striped appearance in the center leaf area. Foliage assumes an overall lighter green color. As deficiency worsens, the symptoms spread throughout the plant.