Studies on Potassium Fractions in Central and Southern Dry Zones of Coconut Growing Areas of Hassan District of Karnataka, India

The experiment was conducted in an order to get an insight about the potassium (K) fractions in Central and Southern dry zone of coconut growing areas of Hassan district, Karnataka during 2022-23. The soil samples from surface (0-30 cm) and sub-surface (30-60 cm) were collected from the soils of selected coconut gardens of Central and Southern dry zones of Hassan district for the study. Results revealed that the average water soluble K, hot water soluble K, exchangeable K, non-exchangeable K, lattice K and total K in surface soils of coconut gardens of Central dry zone of Hassan district registered was 2.76, 9.25, 54.65, 555.35, 5896.00 and 6509.00 mg kg-1, respectively. Whereas the above potassium fractions in sub-surface soil recorded were 2.67, 7.70, 47.36, 699.66, 7282.00 and 8032.00 mg kg-1, respectively. The various forms of potassium in surface soils of Southern dry zone revealed that water soluble K, hot water-soluble K, exchangeable K, non-exchangeable K, lattice K and total K was 2.87, 8.85, 53.51, 546.61, 5603.00 and 6206.00 mg kg-1, respectively. Whereas the above potassium fractions in sub-surface soil recorded were 2.21, 7.20, 45.21, 709.20, 7431.00 and 8188.00 mg kg-1, respectively. The trend of decrease in water soluble K and exchangeable K from surface to sub-surface layers was noticed in soils of Central and Southern dry zone whereas non-exchangeable K, lattice K and total K exhibited an increasing trend with depth. The contribution of each form of potassium to total potassium was in the order of water soluble < hot water-soluble K< exchangeable < non-exchangeable < lattice K. Knowledge of different forms of potassium in soil together with their distribution has greater relevance in assessing the long-term K supplying power of soil to coconut palm and is important in formulating a sound fertilizer program for a given set of soil.