Suitability Evaluation of Alluvial Soils for Rice and Cocoa Cultivation in an Acid Sands Area of Southeastern Nigeria

Two soils, Alfisols and Ultisols were evaluated for swamp rice (Oryza sativa) and cocoa (Theobroma cacao) cultivation. Both soils developed from alluvial deposits in an area dominated by acid sands in Akwa Ibom State of Nigeria. Data were obtained from eight pedons, four from each of the two locations. Both the conventional and the parametric approaches were employed in the evaluation. The result showed that despite the favourable climatic factors and soil physical characteristics, there was no highly suitable (SI) land for rice and cocoa cultivation. By the non-parametric method, potentially and currently, all the soils were marginally suitable (S3) for rice cultivation. But by the parametric approach, currently, 12.5% of the pedons were marginally suitable (S3) while 87.5% were not suitable (N1) for rice cultivation. Potentially, 50% of the pedons were marginal (S3) while 50% were not suitable (N1) for rice cultivation. By the non-parametric method, potentially and currently, 25% of the pedons were moderately suitable (S2) while 75% were marginally suitable (S3) for cocoa cultivation. By the parametric method, potentially and currently, 25% and 75% respectively were marginal and not suitable for cocoa cultivation. The major constraints to rice cultivation were low water table (w), toxicity (t) and soil fertility (f); while those for cocoa were soil physical characteristics (s), toxicity (t) and soil fertility (f).