Potassium availability in soils from different parent materials in the subhumid zone of Nigeria

Abstract

Potassium (K) availability was assessed in 21 soil samples from four different parent materials (alluvium, iron pan materials, Nupe sandstones, and colluvial materials) across the subhumid zone of Nigeria. It was found that the Nupe sandstone soils gave the lowest proportion of the various forms of K with respect to total K in the topsoil. While water‐soluble K was the lowest in the soils of all the parent materials, one normal hydrochloric acid (1 N HCl)‐extractable K was the highest in the soils of all the parent materials. The one normal ammonium acetate (1 N NH4OAc)‐extractable K (exchangeable K) was correlated (P<0.05) with exchangeable calcium (Ca) and magnesium (Mg) in the alluvial, iron pan material and colluvial material soils and with clay in the soils of all the parent materials. The K fixed in the 42 days of incubation was highly correlated (P<0.01) with the K added in the colluvial material soils.