Characterization and Classification of Selected Soil under Different Land Fallow Length in an Ultisol in A Humid Tropical Environment

The study was conducted to characterized and classify selected soil under different fallow length in an ultisol in Ihiagwa, Owerri, Imo state. A target survey was used for the study. Three profile pits were dug on; continuous cropping, three year fallow and seven years fallow. Soil samples were collected from each of the profiles according to their horizonation. The samples were subjected to laboratory analyses using standard procedures. Data obtained were analyzed using analyses of variance and coefficient of variation. The result shows that, the moisture content was higher in the three years and seven years fallow sites (9.54% and 9.89%) respective and least in continuous cropping (8.92%). The Bulk density was higher in the continuous cropping (1.33g/cm3) compared to the three years and seven years fallow that have (1.26g/cm3 and 0.85g/cm3) respectively. The three sites were moderately acidic . The three years and seven years fallow sites recorded high mean value in organic carbon, organic matter, total exchangeable base, and effective cation exchange capacity, compare to continuous cropping site that recorded low value in the soils. There was a low variability in the soil pH, medium variability in the Total Exchangeable acidity and high variability in the Total exchangeable base. The total porosity correlated positively with organic matter and the organic matter also correlated negatively with the bulk density. Using USDA and World Reference Base classification, the continuous cropping and three years fallow soil was classified as Arenic Kandiudults and Arenic Acrisols respectively while the seven years fallow was classified as Typic Paleudults and Chromic Acrisols respectively.