Effects of Toposequence and Soil Depth on Soil Physical Properties of a Typical Alfisols

Management options proffered with respect to the physical properties along a toposequence is a key to sustainable crop and soil productivity since inadequate information on the influence of landscape on soil properties is a major factor limiting agricultural productivity in Nigeria. A study was conducted to evaluate the effect of slope and depth on selected soil physical properties at the University of Ilorin Teaching and Research Farm in 2013. Three points: upper, middle and bottom slope, along a toposequence with an average distance of 200m apart were delineated and samples for soil analysis collected at depths of 0 – 30cm, 30 – 60 cm and 60 – 90 cm using core sampler and auger. Soil physical properties which included sand, silt, clay, saturated hydraulic conductivity (Ksat), bulk density, total porosity, field capacity, permanent wilting point and available water were determined in the laboratory / computed afterwards. Data from the analysis were subjected to ANOVA using 2 x 3 factorial combinations of factors – slope and depth - in randomized complete block design (RCBD) with five replicates. Results indicated that soil texture was loamy sand and sandy loam at the surface and sandy clay loam and clay loam at the sub-surface of the soil. Also, all properties studied were significantly affected by slope and depth except bulk density, total porosity and permanent wilting point for both, and field capacity for depth. Interaction effect was significant for all parameters studied except permanent wilting point at either the 1 or 5 % level of probability.