Potassium replenishment capacity of illitic soils at their minimal exchangeable K in relation to clay mineralogy

Potassium replenishment capacity of eight soil series with varying illite content of their clay fraction were studied at their minimal exchangeable K through green house experiments. Higher minimal K levels were found in soils with high initial K status. Maximum K uptake values were associated with high minimal K. The % illite also had a significant relationship with minimum K levels. Average daily rates of K replenishment of soils varied between 0.25 and 0.67 mg kg −1 soil after reaching minimum K. The K replenishment rates were found highly correlated with minimal exchangeable K (0.96 ** ). Amount of clay failed to attain the level of significance with K replenishment rate. Soils with higher illite content in their clay showed high K replenishment rates.