Potassium dynamics of soils is constituted by constantly changing relationship between soil K forms, and this relation is affected by some soil physical and chemical properties. Most Sidama (south Ethiopia) farmers grow enset crops which have high K requirements. The soils were collected from Awassa-Zuriya and Dale districts; ’Woinadega’ (warm subtropical climate) and Hula district ‘Dega’ (wet, cool temperate climate). Overview of K dynamics in soils via Quantity-Intensity (Q/I) curves was used to evaluate the dynamics of K in fifteen soil samples representing the enset farming systems of Sidama. All of the Hula district soils and half of the Dale district soils had low percent K saturation. There were significant correlations between some soil properties and Q/I parameters and among equilibrium solution parameters and Q/I parameters. Variations among the mean quantity (±∆K) values of the soils were not significant. The Dale and Hula district soils had higher K intensity than the Awassa-Zuriya district soils; where the Hula (Adola kura kebele) soil had the highest value. Therefore, the Dale and Hula district soils will require frequent and split K applications since they have lower capacity to maintain long-term supply of K. On the other hand, Awassa-Zuriya district soils had high K quantity than the Dale and Hula district soils. This shows that the Awassa-Zuriya district soils have a higher potential to supply K for a longer period of time from the exchangeable pool. However, the Awassa-Zuriya district soils require less frequent and higher K fertilization to saturate the exchangeable pool to meet immediate potassium requirement of crops. The low equilibrium activity ratio of potassium and low potassium replenishing capacity of nearly all of the soils studied also indicated the need for K application.
Key words: Dynamics of potassium, potential buffering capacity, activity ratio, quantity-intensity isotherms, potassium saturation.