Saturate hydraulic conductivity, water stable aggregates and soil organic matter in a sandy-loam soil in Ikwuano lga of Abia state

Abstract

A study was carried out along a toposequence in Ikwuano LGA. of Abia state to evaluate changes in saturated hydraulic conductivity (Ksat) and percent water stable aggregates (WSA%). 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 150m apart were delineated and samples for soil analysis collected from two depths (0-15cm and 15-30cm) using core samplers and auger. Samples were collected from each topo-unit at the respective depths in triplicate. Samples were analyzed for soil properties like; Ksat, WSA (%) and percent organic carbon (OC %), Data from the analysis were subjected to ANOVA using a split plot in RCBD. Results indicated that for both slope positions, WSA, Ksat and OC were significantly different with depth (P≤ 0.01). These properties also varied significantly (P<0.001), along the toposequence. With increase in WSA, Ksat and OC also increased. Simple linear correlation between WSA %, Ksat and OC % showed that at shallow depth (0-15cm), there was a significant and direct relationship between WSA and Ksat, WSA and OC and, Ksat and OC (P<0.01). Organic carbon accounted for 28% of the stability of aggregates as well as the degree of water movement in the saturated soil column (Ksat), at the shallow depths, while deeper in the soil column, (15-30cm depth), only WSA and OC showed significant (P<0.01) relationship with more than 70 % of the stability of aggregates accounted for by the organic carbon content of the soil. .

Keywords: Toposequence, Water stable aggregates, Saturated hydraulic conductivity, Organic carbon, Slope position.

Agro-Science Vol. 4 (1) 2005: pp. 34-37