Potassium Release from Clay Micas

In view of anomalous crop response to K fertilizer treatment in alluvial soils of India (enriched with fine grained micas), clays of six Soils, two each from semi-arid (SA), moist sub-humid (MSH) and per humid (PH) climatic zones, were subjected to repeated batch type Ba-K exchange to follow the rate of K release with respect to nature and content of mica. The decrease in the X-ray intensity ratio of peak heights of 001 and 002 reflections of mica after the Ba-K exchange suggested that the K release is governed by only nature of clay mica. Rapid K release in SA and MSH clays was due to higher biotite content while the much reduced rate in PH clays was because of mica with more muscovitic character.