Characterization and classification of soils on a toposequence around Dutse Jigawa State, Nigeria

Soil characterization and classification is extremely important for land use planning and environmental conservation. The aim of the current study was to characterize and classify the soils present in a toposequence established at the Nigerian Institute for Oil Palm Research (NIFOR) Jigawa state, North-Western Nigeria. Four representative soil profiles were excavated at the crest, upper, middle and lower slope positions in the study area. Across the soil horizons, the textural classes varied from sand to loamy sand, and the bulk density was between 1.21 and 1.55 g cm− 3 in the surface and sub-surface horizons. Soil pH ranged between 4.7 and 7.7 in the surface and sub-surface horizons. Soil organic carbon, cation exchange capacity and available P ranged from 0.88 to 1.61%, 3.54 to 7.17 cmolc kg− 1 and 1.95 to 3.50 mg kg− 1 respectively. The percent base saturation was low to high (30.36–80.00%), with the dominant soluble cations being Ca2+ and Mg2+. The extractable micronutrients in the soils were medium (Fe), low to medium (Mn), low (Zn) and very low (Cu). The soils at the study site were classified as Entisols at the order level of USDA, which correlate to Arenosols in the (FAO/WRB) reference soil group. The quality of the NIFOR soil was divided into five levels, with grade I, being the highest and grade V the lowest. The proportion of grade II and IV soils were the largest, at 26.39% and 23.64% respectively, with grade III being the smallest at 11.17%. The data collected from this study are critical for the development and interpretation of effective, site-specific management practices. Based on the data obtained, soil conservation techniques including continuous organic matter incorporation and mineral fertilizer application to the soils would markedly improve their fertility for agricultural purposes.