Potassium Fertility Inter-Relations in Rice Soils

The study quantifies the different forms of potassium and investigates the inter-relationships of these forms with other soil fertility parameters.Soil samples from two major wet land rice soils of Kerala viz., lateritic alluvium of Pattambi (brown hydromorphic) and Onattukara sandy soil ( greyish Onattukara) of Kayamkulam were studied. A laboratory incubation study to monitor the dynamics of native as well as applied K were investigated.The lateritic alluvium of Pattambi was clayey. high in chloride, organic matter, active iron, CEC, ECEC, exchangeable Ca, Mg and sum of bases and was low with respect to coarse sand and available phosphorus contents and was less acidic as compared to the Onattukara sandy soils of Kayamkulam. The latter was loamy sand in texture with a high content of coarse sand fraction, more acidic,high in phosphorus content and low in clay, chloride, organic matter, active iron, CEC, ECEC, exchangeable Ca, Mg and sum of bases in comparison to the former.Fractionation studies revealed that the Pattambi soils had a higher content of total K, HNO3K and fixed K as compared to that of Kayamkulam soils.Potassium fixation was found to be a constraint in Pattambi soils.