International Journal of Horticulture and Agriculture Research ISSN(print): Applied, ISSN(online): Applied Volume 01 Issue 01 June 2025 Page No: 37-47 37 Volume 01 Issue 01 June 2025 Corresponding Author: Nnabuihe, E. C Profile Characteristics and Classification of Selected Ultisols Under Varying Land Use Types in Owerri Southeastern Nigeria Nnabuihe, E. C. 1 *, Chukwu, E.D. 5 , Apalowo, O.A. 2 , Ugochukwu, G.U. 4 , Osisi, F.A. 5 , Madueke, C.O. 1&6 , Mbe, J.O. 7 , Chukwu, O 3 , Onunwa, A.O 1 , Chukwuma, T.R 1 , Uko, I. 2 1 Department of Soil Science and Land Resources Management, Nnamdi Azikiwe University Awka Anambra state Nigeria 2 Department of Crop Science and Horticulture, Nnamdi Azikiwe University Awka Anambra state Nigeria 3 Department of Forestry and Wildlife, Nnamdi Azikiwe University Awka Anambra state Nigeria 4 Department of Bioenvironmental Science, Morgan State University Baltimore MD, U.S.A 5 Department of Soil Science and Technology, Federal University of Technology Owerri, Imo state Nigeria 6 Institute of Soil Science and Land Evaluation, University of Hohenheim, Stuttgart, Germany 7 National Root Crops Research Institute (NRCRI) Umudike, Abia State Nigeria ABSTRACT: Land use changes have profound impacts on soil properties, especially in fragile tropical ecosystems. This study evaluated the morphological, physical, and chemical properties of soils under four contrasting land uses: oil palm plantation, secondary forest, industrial cluster, and housing estate in Owerri, Imo state Southeastern Nigeria. Eight representative soil profiles were described and sampled across the land use types, and a total of 37 soil samples were analyzed in the laboratory. Morphological properties revealed deep, well-drained profiles with variations in horizonation, colour, structure, and root abundance across land uses. Forest and oil palm soils exhibited better developed profiles, finer granular structures, and higher OC contents, while soils in industrial and residential areas showed signs of compaction and structural degradation. Chemical analyses indicated strongly to very strongly acidic soils (pH 4.2–5.9), low OC (0.28–1.52 g/kg), low TN, and low BS (<50%) in most subsoil horizons. Exchangeable Al3+ and Na+ were high in industrial and residential soils, indicating risks of Al3+ toxicity and sodicity. The presence of clay illuviation in all profiles confirmed the development of argillic horizons. Soils were classified as Typic Kandiudults and Alic Kandiudults under USDA Soil Taxonomy, and as Haplic and Arenic Acrisols under the WRB system. The results underscore the role of land use in shaping soil quality and provide a basis for sustainable soil and land management strategies in rapidly urbanizing tropical regions. KEYWORDS: Land use change, Ultisols, Soil classification, Acrisols, Owerri, Southeastern Nigeria INTRODUCTION Soil serves as a fundamental component of terrestrial ecosystems, and plays a vital role in food production, nutrient cycling, water regulation, and climate change mitigation. However, it is inherently vulnerable to anthropogenic pressures, particularly land use change and intensive land management, which can significantly alter its physical, chemical, and biological properties (Nnabuihe et al., 2024). In tropical regions such as Sub-Saharan Africa, soils are often highly weathered and low in inherent fertility, making them highly susceptible to degradation under inappropriate land use (Critchley et al., 2023). In Nigeria, and particularly in the southeastern region, rapid urbanization, population growth, and the expansion of industrial and residential infrastructure have led to widespread transformation of natural landscapes (Ayo-Odifiri, 2025). These land use changes often result in soil compaction, erosion, organic matter depletion, and nutrient imbalances (David Raj et al., 2024, Naik et al., 2025). Conversion from forest to anthropogenic land uses such as plantations, housing estates, or industrial zones accelerates these changes, often compromising soil structure, reducing infiltration capacity, and increasing acidity and base cation depletion (David Raj et al., 2025). Understanding how soil properties vary under different land uses is critical for guiding sustainable land management and maintaining long-term productivity. Soil morphological characteristics—such as horizonation, colour, structure, and consistence, alongside chemical attributes such as pH, organic carbon (OC), total nitrogen (TN), available phosphorus (AP), cation exchange capacity (CEC), and exchangeable cations, provide valuable indicators of soil quality and degradation status (Yousif et al., 2025). Soil classification systems such as the USDA Soil Taxonomy and the World Reference Base for Soil Resources (WRB) offer standardized frameworks for interpreting soil genesis, behaviour, and suitability for various land uses (Soil Survey Staff, 2022,