Phosphorus fixation capacity and its relationship with the soil characteristics in laterite soils of Karnataka

Phosphorus fixation capacity of surface soil samples was determined in six soil series of coastal and hilly regions of Karnataka, where rice is grown mainly under rainfed situation. Two methods viz. conventional method (Waugh & Fitts 1966) and the method suggested by Hunter (1988) for evaluation of P fixation capacity of soil were compared. Soil samples were analyzed for physical and chemical properties and the relationship between the P fixation capacity and the soil properties were statistically worked out. The results revealed that P fixation capacity of soils exhibited rise with increase in the levels of applied P. Phosphorus fixation values were found to be relatively higher in the conventional method, as compared to the Hunter's method. Among the six soil series viz., Anajur, Belagola, Brahmavara, Heroor, Kapikadu and Someswara series, the fixation of P was the highest in Brahmavara series and the lowest in Kapikadu series. Phosphorus fixation capacity of soil showed significant and positive correlation with organic carbon and available P content.