Dynamics of Potassium in Representative Soil Series of Southwestern Nigeria

Abstract

Experiments were carried out to evaluate the dynamics of potassium (K) in six representative soil series of southwestern Nigeria to provide guidelines on soil K management. Quantity–intensity (Q/I) approach was used and the Q/I isotherms obtained revealed that all the soils released K before reaching equilibrium, having a negative intercept. The results showed that labile K from the Q/I evaluation was greater than exchangeable K from ammonium–acetate extraction in all the soils, showing that evaluation of soil K by exchangeable K alone may not give an in-depth understanding of the K dynamics in soil. Hence, it should be used in addition to Q/I parameters for a reliable evaluation. The potential buffering capacity obtained ranged from 0.4983 to 1.4272 cmol kg⁻¹/(mol L⁻¹)^1/2, indicating that the soils have a low capacity to maintain K concentration for a long period and hence would require frequent K fertilization.

Keywords:

• exchangeable potassium
• labile potassium
• potassium dynamics
• potential buffering capacity
• quantity–intensity isotherms
• soil series