Capability groupings of some nun river floodplain soils of Bayelsa State, Southern Nigeria

Abstract

Nine Nun River floodplain soils in Bayelsa State were evaluated using Land Capability Classification (LCC), Land Capability Index (LCI) and Fertility Capability Classification (FCC) systems. The LCC grouped most soil mapping units (SMUs) into class II except NDU3. Odi (ODI1), Koroama (KRM1) and Niger Delta University (NDU1) were grouped in IInf0; ODI2, KRM2 and NDU2 in IIwnf0; ODI3 and KRM3 in IIwnf1 and NDU3 in Vwnf3, respectively. Indicating suitability for wide range of arable crops. The LCI grouped ODI1, KRM1 and NDU1 in class II while ODI2, ODI3, KRM2, KRM3, NDU2 and NDU3, in class III for annual crops. For perennial crops, KRM1 and NDU1 were grouped in class II, ODI1, KRM2 and NDU2 in class III while ODI2, ODI3, KRM3 and NDU3, in class IV, respectively. The FCC grouped ODI1 in La- and ODI3 into Lga-e. On the other hand, KRM1 was grouped in La-e while KRM2, KRM3 and NDU3 in Lga-ek. The identified limiting fertility constraints were wetness, flooding, low exchangeable K⁺, Ca²⁺ and Mg²⁺ concentration, soil acidity as promoted by Al³⁺ toxicity, texture and drainage. LCI and FCC identified texture as a major constraint with LCI placing emphasis on soil colour while FCC identified K⁺ deficiency as a limitation. Wetness, flooding, low nutrient capital of exchangeable K⁺, Ca²⁺ and Mg²⁺, soil acidity and Al³⁺ toxicity, texture and drainage were key to land evaluation in the study area. Flood control, improved drainage, liming and adequate fertilization practices including organic matter conservation should be adopted for improved land management.