What form of potassium is considered most available to plants?

The most available form of potassium to plants is solution potassium. This is because solution potassium refers to potassium that is dissolved in soil water, making it accessible for plant uptake through their roots. Plants require nutrients in a soluble form for effective absorption, and solution potassium meets this requirement by being readily available for immediate use.

Organic potassium, while it can contribute to long-term soil fertility, is not immediately available to plants as it needs to be mineralized into simpler forms first. Potassium salts are often used in fertilizers and can release potassium in soluble forms, but unless they dissolve in soil moisture, they may not be immediately available. Slow-release potassium fertilizers, while designed to gradually provide nutrients over time, do not offer the quick availability that solution potassium does. Therefore, solution potassium stands out as the most directly available form for plant uptake.