EVALUATION OF THE PHYSICO-CHEMICAL AND MORPHOLOGICAL PROPERTIES OF AN EXPOSED SOIL PROFILE IN AN EXCAVATED ACRISOL, SOUTHEAST NIGERIA

Abstract

Increased population density has led to a lot of pressure on the limited natural/land resources of south-eastern Nigeria. This includes the need for laterite, sand, kaolin, gravel and clay for buildings, backfills and road construction. This has led to extensive unmoderated excavation of these resources, particularly in Anambra state. The excavation has in turns, culminated in increased intensity of land degradation in the state, underscoring the need to characterize and evaluate the land use potentials of such sites to better understand the nature of the soils and the impacts of the attendant land use. Samples were collected from the different horizons of the profile to evaluate the physical, chemical and morphological properties of the soils. Coefficient of variation was used to measure the soil variability within the profile. Land capability class was determined, which informed the land use and management recommendations. The results show that the soil is very deep (>21.5m). The soil texture ranged from sandy clay loam to sandy. Infiltration rate and saturated hydraulic conductivity decreased by up to 300 to 560 % with excavation. The soils were strongly acidic; organic carbon and total nitrogen was low but highly variable; Al, H, Ca, Mg, K, Na, and phosphorus were moderately variable while pH, CEC and base saturation (BS) were the least variable. The land capability class was IIIes. Given the evidence of erosion and preponderance of erodible Nanka sands in the subsoil, the site should be reclaimed as soon as the mining activities are discontinued.

Keywords

• land degradation
• soil excavation
• soil profile
• sand mining
• open pit mining