Influence of Cropping Systems on the Characteristics and Fertility of Beach Soils in The Niger Delta Area of Akwa Ibom State, Nigeria

The influence of cropping systems on the characteristics and fertility of soils derived from beach sands was investigated. The study site was the Cross-River Basin farm, Onna Local Government, in the Niger Delta area of Akwa Ibom State, Nigeria. Two cropping systems- sole cropping (SC) and mixed cropping (MC) and fallow plot [FP] as control, were examined. Pineapple (Ananas commosus) plot and water melon (Citrullus lanatus) plot, represented SC. Plantain/cassava (Musa spp/Manihot esculenta) plot and water leaf/scent leaf (Talinum triangulare L./Ocimum grattissimum) plot represented MC. Representative soil samples were collected at 0-15 and 15-30 cm depths from each plot for laboratory analysis. The result showed that irrespective of cropping system or soil depth, total nitrogen [N] and exchangeable potassium (K) were low ? (values below critical levels: < 0.15% and < 0.20 cmol/kg, respectively). Available phosphorus (P) was medium 8 ? 20 mg/kg) at both depths in the pineapple plot, and high (> 20mg/kg) at both depths in all others cropping systems. Organic matter (OM) was low (< 2%) in the plantain/cassava MC, and medium (2 ? 3%) in other cropping systems, at 0 ? 15 cm depth, but at 15 ? 30 cm, OM was medium in water melon SC and plantain/cassava MC and low in other cropping systems. Exchangeable bases (Ca, Mg, K) and P were highly variable (coefficient of variation (CV), > 35%) within each cropping system. Analysis of variance (ANOVA) test showed that, irrespective of soil depth there were significant differences (P ? 0.05) among the cropping systems in 11 (79%) of the 14 soil characteristics tested. In view of the deficiencies and variations in soil fertility, regular soil testing for proper fertilizer recommendations is essential to ensure balanced soil nutrient application. Also, well planned crop combinations and rotation programmes will ensure optimum and sustainable land productivity, improved ecological balance and environmental quality.