Improving the Efficiency of Ammonium Acetate Extraction of Soil Potassium by Saturation Extract Method

The K-status in soils and its availability to plants has close relationship with field capacity or saturated conditions. Hence, there is a need to know the available K status through saturation extract and other parameters governing K-availability which bears close relation to normal field situation under which plants are grown. To improve the efficiency of ammonium acetate method by saturation extract method, saturation extract parameters were studied in vegetable growing soils of Ranga Reddy and Mahaboobnagar districts of Telangana and are correlated with forms of potassium, soil physical and chemical properties to know the importance of these parameters in release and availability of K to plants. The saturation extract obtained from the soils was analysed for available potassium and Ca + Mg values. Different parameters of the saturation extract viz., CRK, BCK and USQI factor were calculated to know the availability of potassium to plants. Results of correlation between BCK and USQI with exchangeable and non exchangeable K showed that these parameters influence the release and availability of K to plants and also the correlation with soil characteristics clearly indicate that the quantity factor Kam, KL and intensity factors PBCK, BCK are important to assess available K status. These parameters derived from K extracted by NN NH4OAc and concentration ratio of K in the saturation extract of soil i.e. BCK and USQI factor served as better indices for assessing the K supplying status of soils than K extracted by different chemical methods.