Forms of Primary Nutrient Elements in Soils Overlying Contrasting Parent Materials in South - Eastern Nigeria

Appropriate management of soil fertility should rely upon sound knowledge of the nutrients reserve and their availability. This is only possible if there is adequate information on the influence of parent material on the dynamics and availability of these nutrient elements. Research was carried out in 2014 at three locations underlain by three different parent materials namely Basalt (Ikom in Cross River State, Sandstone (Nto-Ndang in Akwa-Ibom State) and Alluvium (Ohaji-Egbema in Imo state) to provide information on the status and dynamics of the major primary nutrient elements (N, P, K) in the soils of these areas. Results showed that Basalt-derived soils were more clayey, contained higher quantities of organic matter and exchangeable bases (TEB) than soils of other parent materials. Significantly (P<0.05) higher proportions of total P (1383 mgkg-1), organic P (974 mgkg-1) and active inorganic P (275.4 mgkg-1) were recorded in soils derived from Basalt than other parent materials. Significantly (P<0.05) higher total nitrogen (2.90 mgkg-1) was recorded in Basaltic soils than soils developed on Sandstone (1.8 mgkg-1) and Alluvium (1.3 mgkg-1). Available nitrogen and potassium contents of the soils of the varying parent materials did not differ significantly (P<0.05). The highest quantity of total K (198 mgkg-1) was recorded in soils derived from Sandstone compared to those of Basalt (119 mgkg-1) and Alluvium (106 mgkg-1). Soil primary nutrient elements (potassium and phosphorus) varied due to parent materials while no variation was obtained in the nitrogen contents of the soils of the different parent materials investigated. It is therefore, recommended that in soil fertility studies, the primary nutrient element contents of soil lithological materials should be considered.