Inherent Defects Associated With Original Construction Methods and Materials Used For Earth Buildings in Nigeria: Case of Gbongan Rural Communities in Osun State (Published)
The durability and longevity of an earth wall is dependent as much upon the raw materials originally employed and methods of which the traditional building was constructed. This research addresses the analysis of the pathologies present in a sample of 120 cases of traditional earth building at Gbongan rural area in Osun State. The defects identified are related with construction methods in which they are detected. The soil particle distribution of earthen material was analysed, soil properties which make soil a suitable construction material are discussed. The paper then concludes on some earth property tests such as composition, consistency, dry shrinkage, coefficient of expansion that enhance durability of earthen structure.
Potassium Forms in Particle Size Fractions of Soils on a Toposequence in Mbano, Southeastern Nigeria (Published)
Potassium distribution of a toposequence provides management information for landscape sustainability. Potassium forms (total, structural, Fixed, Available, Exchangeable and Solution) in bulk and particle size fractions of soils on a toposequence in Mbano, Southeastern Nigeria were studied. Total, structural, fixed, available, exchangeable and solution K in bulk soil, sand, silt and clay particle size fractions ranged between 0.44-0.88, 0.21-0.59, 0.09-0.22, 0.13-0.33, 0.09-0.22 and 0.04-0.11 and 0.45-0.73, 0.05-0.27, 0.06-0.20, 0.11-0.26, 0.07-0.17 and 0.04-0.08 cmol+ kg-1 in A and AB horizons respectively. Also, concentration of most K forms in bulk soil and particle size fractions decreased in the order total > structural > available > fixed > exchangeable > solution for both horizons. Equally, within each horizon K forms varied with physiographic positions (summit, mid-slope and toe-slope) with concentrations of bulk soil, sand and clay particle size fractions better in the summit and that of the silt size fraction in the toe-slope of the A horizon while those of bulk soil and all particle fractions size fractions better in the toe-slope of the AB horizon. Furthermore, in each physiographic position, K enrichment of soil particle size fractions for A and AB horizons decreased in the order clay > silt > sand. Bulk soil and particle size K fractions correlated (P < 0.05) with soil ECEC, pH, OM, P, total N, sand, silt, clay and silt/clay ratio. In, general distribution of K forms in particle size fractions along a toposequence suggests the need for consideration of active soil portions for sustainable K management of the environment.