POTASSIUM STATUS OF RED SOILS UNDER DIFFERENT LAND USE SYSTEMSH.V. Rudramurthy and Y.P. Shilpashree
Six red soil profiles under current fallow, mixed forest, paddy, sugarcane, tobacco and areca nut land use systems from Southern Transition Zone of Karnataka were excavated, horizonwise soil samples were collected, processed and analyzed for available k content and selected soil properties. Solum weighted average values for available potassium varied from 68 Kg K2O/ha in current fallow land use system to 638 Kg K2O/ha in areca nut land use system In general, increasing trend of available K down the profile in the subsoil solum of the soils under both current fallow and paddy land use systems and in the upper solum of the soils under both mixed forest and sugarcane land use systems could be attributed to co-migration of potassium with clay down the profile. Available potassium status in the surface horizons of soils under cultivated land use systems were high and this could be attributed to the regular application of higher doses of potassic fertilizers and subsequent build up of potassium in soils as the crop requirement of potassium is far less than regular application of higher doses potassium. Correlation studies indicated that among the soil properties studied, available potassium was positively and significantly correlated with exchangeable basic cations (0.538**) and silt (0.348*), while with other soil properties including organic carbon its relationship was non-significant. Positive and non-significant correlation of potassium with organic carbon suggested that available potassium mostly included inorganic potassium.
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