Forms of Potassium in Relation to Soil Moisture Regime

The relationship of soil moisture regime vis-a-vis stage of weatherability on distribution of different forms of potassium was studied in sandy and coarse loamy soils of Rajasthan. The soils belonging to aridic soil moisture regime comparatively younger in weathering stage have higher content of all forms of K, except fixed K, followed by weak aridic and ustic soil moisture regime. Fixed K shows an inverse trend as compared to other forms of K. The content of water soluble K and exchangeable K, mineral K and total K increased with narrower very fine sandi fine sand ratio (VFS/FS) and wider Al₂/Fe₂O₃ molar ratio. However, fixed-K showed an agreement with wider VFS/FS ratio and narrower Al₂/F₂O₃ molar ratio. The wider fixed K to exch. K ratio indicated rapid conversion of fixed K to more available forms in soils belonging to ustic soil moisture regime.