THE DYNAMICS OF POTASSIUM (K) IN REPRESENTATIVE SOIL SERIES OF GHANA

Abstract

The immediate supply of K by soils to growing plants derives mainly from the K that is labile whereas the long term K nutrition of plants depends on the non-labile K. The dynamic relationship between these forms of K constitutes the dynamics of K in soils. Most Ghanaian farmers grow root and tuberous crops which have high K requirements. Knowledge of K dynamics in soils is therefore essential for K management to sustain crop production and management of agroecological environments in Ghana. Quantity-Intensity isotherms provide a better overview of K dynamics in soils. Therefore, Quantity/Intensity (Q/I) curves were used in this study to evaluate the dynamics of K in ten soil series representing the major agro-ecological zones of Ghana. K dynamics in the soils were found to be influenced by some soil properties. Significant correlations were found between soil properties and Q/I parameters; and among equilibrium solution parameters and Q/I parameters. There was no significant variation among the mean quantity (±∆K) values of the soils. The savannah soils had higher non-specific K, K-potential, and potential buffering capacity (PBC K ) than the forest soils; and the Akuse series had the highest values for these parameters. However, the forest soils had higher K-intensity. Therefore, the forest soils will require frequent and split K applications since they have lower capacity to maintain long-term supply of K. However, the savannah soils will require less frequent but higher K fertilization to satisfy the exchangeable pool and immediate plant nutrition requirement.