Pedological Characterization and Classification of Typical Soils of Lupane District, Zimbabwe

Abstract

Pedological characterization and classification of soils is key for land resource planning and development of soil management interventions for improving agricultural productivity. A study was conducted in Bubi area of Lupane District, Zimbabwe, to examine soil morphological, physical and chemical attributes and to classify soils for land use planning and determining area specific soil management strategies. A detailed soil survey was conducted using a free survey method. Five soil mapping units M1, M2, M3, M4 and M5 were delineated and mapped based on field observations and laboratory analysis results. Soil samples were collected from representative profiles of each mapping unit for soil physical and chemical analyses. Sandy and loamy sand textures were dominant for surface soils while sandy clay loam and sands were dominant in subsurface soils. Mapping unit M3 had an abruptic textural change with sandy surface textures overlying sandy clay loam subsurface soils. Soil pH was alkaline (7.0 – 7.4) in deeper subsurface layers of M1, M2 and M4 mapping units. Exchangeable magnesium (Mg2+) and calcium (Ca2+) were the dominant exchangeable cations. The level of exchangeable Ca2+ for both surface and subsurface soils was low (< 5 cmol(+)kg-1). Clay content had highly significant positive correlations with cation exchange capacity (CEC), exchangeable Ca2+, Mg2+ and soil pH. CEC had highly significant positive correlations with silt, soil pH, exchangeable Ca2+, Mg2+and Na+. According to the ‘World   Reference Base for  Soil Resources’ classification system, soil units M1, M2, M3, M4 and M5 were classified as Calcic VERTISOLS, Haplic LUVISOLS, Haplic LIXISOLS (abruptic), Luvic CALCISOLS (Chromic) and Rubic ARENOSOLS (dystric) respectively. Clay content and CEC significantly correlated with most soil chemical properties in the study area. Liming, split fertilizer application and organic matter additions was recommended to address fertility issues related to high sand content, soil acidity, low CEC, low exchangeable Ca2+ and K+ constraints identified in some mapping units.