Preliminary Assessment of the Potassium Buffering Capacity of Selected Arkansas Soils.

Potassium (K⁺) is one of the plant nutrients used in large quantities by Arkansas farmers to maximize crop yields. Although total soil K⁺ exceeds crop uptake during the growing season, only a small fraction of this K⁺ is available to plants. In soils, K⁺ is found in equilibrium among four phases which are: solution, exchangeable, non-exchangeable, and structural, with the interaction among those phases determining the availability of K⁺ for plant uptake. It is well known that soils differ on their ability to replenish soil solution K⁺  due to plant uptake and that a better understanding of the kinetics of K⁺ release would improve the accuracy of soil testing to derive fertilizer recommendations. Soil samples varying in soil texture and testing low in exchangeable Mehlich-3 K⁺ levels were collected from several regions in Arkansas, with the objective of characterizing their Quantity/Intensity relationships (buffer power). Preliminary results of this effort will be presented.