Nonexchangeable potassium extraction and associated structural changes of mica dominant clay minerals

Abstract

Six mica dominant soils representing a landform sequence were used for the present investigation. The effect of extraction of nonexchangeable potassium (K) by boiling 1 M HNO 3 treatment and its associated structural changes of micaceous clay minerals was studied by employing x-ray diffraction technique. Potassium release was rapid in the first three extractions and slowed down to a constant rate thereafter in all the clay samples. The first extraction contributed about 45.57-62.69% towards the total K release. The calculated values of rate constant (first order) decreased sharply from 0.065-0.025 min -1 after third extraction and reached a constant value thereafter. The calculated integral width of first order reflection of mica peak (10Å) decreased 1 Corresponding author (present address: