ABSTRACT

A study was carried out along a topo sequence in lkwuano L.G.A of Abia State to evaluate changes in soil physical and chemical properties. Five points: crest (A), upper slope (B), middle slope (C), lower slope (D) and valley bottom (E), along the toposequence with an average distance of about 1 50m apart were delineated and samples for soil analysis collected from two depths (0 -15cm and 15-30cm) using core saniplers and auger analysis. Samples were• analyzed for soil properties, namely: aggregate stability (AS), bulk density (BD), saturated hydraulic conductivity (Ksat), percent organic carbon (%OC), percent total nitrogen (%N), cation exchanges. capacity (CEC), available phosphorus (Avail. P), particle size distribution, and pH in H20 and in KC1. Data from the analysis were subjected. to ANOVA using split plot in RCBD. Results indicated that for both depths of sampling, the soil textural class ranged from loamy sand to sandy loam, while pH ranged from acidic to slightly acidic. Properties such as AS, BD, Ksat, %N, CEC and %OC were significantly different with depth at a probability level ranging between 0.01 and 0.001. However, along the toposequence, BD did not vary significantly but increased with depth. while all the other properties assessed varied significantly at P < 0.001. With increase in AS, Ksat and °/0OC also increased while BD did not increase. Simple correlation between AS,. Ksat and percent OC showed that at 0-1 5ciri depth there was a significant direct relationship between AS and Ksat, AS and percent OC and, Ksat and percent OC at P < 0.05. On the other hand, at the 15-30cm depth, only AS and percent OC showed significant (P < 0.01) relationship. These results therefore, indicate that all physical and chemical properties (except BD) studied varied significantly along the toposequence. The variation were either positive or negative depending on the depth of sampling or slope positions.