Soil Characterization and Classification on Varying Lithology in Imo State South Eastern, Nigeria

The field study was carried out in Okigwe South-eastern Nigeria.  Three profiles were sunk in soils of each of each parent material. Soil samples were subjected to routine and standard laboratory analysis for selected physic-chemical properties. The morphological and physic-chemical properties of the soils varied widely, sand-size particles dominated other particle sizes with the mean values of 448g/kg, 538g/kg, 648g/kg on sandstone, while soils derived from Imo clay shale were 738g/kg and 578g/kg Amuro, 1 and 2, respectively. Clay in Imo shale was highest at Amuro pit 2, 312g/kg and 416g/kg Nihort 1 of false-bedded sandstone. The highest value of bulk density was recorded in Nihort 1, 15g/kg, and 16g/kg Amuro 1, respectively. All the pedons exhibited sandy clay loam on topsoil and relatively more clayey subsoil. The pH of the soil varied from very strong acidic (pH 4.5) to slightly acidic (pH 6.2) in all the soils, except for Amuro pit 2 which had moderately alkaline to strongly alkaline pH 7.9 – 9.05. The pH of the soil varied from very strong acidic to slightly acidic in all the soils, except from Amuro pit 2 which had moderately alkaline to strongly alkaline. Amuro pit 2 had high base saturation 98.0% with no exchangeable aluminum. Others had low to moderate base saturation. Cation exchange capacity was highest at Amuro 1. Moderate to low organic matter and variation was recorded in Amuro 2 except for clay, organic matter, and Ca: Mg ratio. Soils from Nihort 1,2 and 3 and Amuro were classified as class II of the USDA capability classification system. It is observed that the soils of the two parent materials sustains agricultural yield if proper land use practice is adopted.

Keywords: Classification, Soil, Physiochemical properties, Imo clay shale, false bedded sandstone