Rocks as fertilizers: preliminary studies on potassium availability of some common rocks in Sri Lanka

J. M. NIWAS and C. B. DISSANAYAKE Abstract Preliminary investigations of the K availability of some commonly occurring rocks of Sri Lanka showed that granulitic gneiss, pink granite, migmatitic gneiss and microcline granite release relatively high amounts of K indicating the capability of using these to provide K in plant nutrition. The finer crushed sizes are more effective in releasing K, and the availability of the K-reserves under appropriate soil conditions makes them possible substitutes for synthetic K fertilizers. Download