Soil hydraulic and physico-chemical properties of Ultisols and Inceptisols in south-eastern Nigeria

Understanding soil water dynamics and storage is important to avoid crop failure on highly weathered, porous and leached soils. The aim of the study was to relate soil moisture characteristics to particle-size distributions and chemical properties. On average, Atterberg limits were below 25% in the A-horizon and not more than26.56% in the B-horizon, whereas soil bulk density was between 1.27 and 1.66Mgm−3. The saturated hydraulic conductivity (Ksat) was generally between 0.20 and 5.43 cm h−1 in the top soil and <1.31 cm h−1 in the subsoil. The higher Ksat values for the A-horizons were attributed to the influence soil microorganisms operating more in that horizon. The amount of water retained at field capacity or at permanent wilting point was greater in the B-horizons than in the A-horizons, suggesting that clay accumulation in the B-horizon and evapotranspiration effects in the A-horizon may have influenced water retention in the soils. Soil moisture parameters were positively related to clay content, silt content, exchangeable Mg2+, Fe2O3 and Al2O3, and negatively related to sand content, SiO2, sodium absorption ratio, exchangeable sodium percentage and bulk density. The low clay content may explain why drainage was so rapid in the soils.