Origin of Native Potassium in Alonso Soil

Abstract

Kaolin and illite were identified in the clay fraction of Alonso soil. The relative concentration of kaolin to illite in the 2.0-0.2 µ fraction was greater than double throughout the profile, while in the less than 0.2 µ fraction, it was about the same for profile depths down to 3 feet. Illite seems to predominate over kaolin at lower profile depths. The total potassium content of the clay fraction less than 0.2 µ corresponded with the observed trend in illite variation. Illite was found to be the only soil mineral source of native potassium in Alonso soil.