Potassium Availability and Release Behaviour in Earthworm Casts and Non-ingested Soils

Samples of earthworm casts as well as of surrounding non-ingested soils were obtained from 15 different locations to study potassium availability and the mode of release of K under earthworm activity. Considerable increase in the K extracted by different extractants from the wormcasts over non-ingested soil was observed. The difference between K extracted from casts and non-ingested soils became smaller as more stronger extractants were used. Larger amounts of K were determined in the soils collected from beside a house followed by those under fruit crops while the smallest amount was found tinder grass habitation. Using first order kinetic equation, the K release behaviour was studied. Higher K release constants (a) were recorded for the casts than for non-ingested soil.