The physical properties of some soil profiles and management of an erosion prone soil in southwestern Nigeria

Abstract

Infiltration, ease of root penetration, retention of plant nutrient, availability of water within crop rooting zone and soil proneness to erosion are all intimately connected with the physical properties of the soil. A study was conducted within the Teaching and Research Farm of University of Ibadan, Western Nigeria to investigate the physical properties of an erosion prone soil. Three profiles were dug along a 60 m toposequence and core samples collected at depth of 0 - 7 cm, 8 - 15 cm 15 - 45 cm, 45 - 75 cm and 75 - 105 cm. The textures of the subsoil were; sandy clay, sandy clay loam or sand. This light texture indicates that the soil is highly susceptible to degradation by human and animal agents. Clay content increased down the profile whereas fine sand fraction distribution was uniform along the toposequence. The soil bulk densities values ranged from 1.65 - 1.83 g cm-3. Total porosity values where low (< 40 %) indicating that the soil is ‘unsatisfactory’ for crop production. The soil hydraulic conductivity class was the “very slow” type except at the upper slope which was moderate. This “very slow” conductivity nature of the soil could cause water deficit in crop rooting zone and build up runoff with little rainfall or irrigation. This implies the soil is susceptible to erosion. Variability of bulk density was low (CV < 15 %), whereas that of gravel, clay fractions and hydraulic conductivity were consistently high (CV > 35 %). Coarse and fine sand fraction were consistently moderately variable (CV = 15 - 35 %). Minimum tillage will offer great advantage when combined with surface mulch. Strip cropping, use of fertilizer of organic origin and cover crops will improve organic matter of the soil, soil stable aggregates, soil porosity and infiltration. Uniform soil management along this toposequence should be avoided.

Key words: Binders, processing, water stability.