ABSTRACT

Land use changes from forest into cultivated ecosystems result in negative impact on soil

structure and quality. The purpose of this study was to determine effect of land use and

slope on selected properties and quality of an Alfisol in Afaka forest, Northern Guinea

savanna of Nigeria. Land use systems, including natural forest and cultivated land were

identified. Eighteen (18) composite disturbed and undisturbed samples were collected

from depth of 0-5 and 5-10cm for analysis of pertinent soil properties in the laboratory

using rigid grid procedure. Most physical and chemical properties show relative

variations in response to land use types and geomorphic positions. Mean weight diameter

(MWD) indicates higher water stable aggregates of 1.26 mm in forestland and less stable

aggregates in cultivated land 1.19 mm. Textural classes of soils under all the land uses

on different topographic positions were sandy loam. Results indicate that the soils had

high degree of weathering potentials, low to moderate bulk density at 0-5cm depth

values range between 1.42 to 1.49 Mg m-3 in forest and cultivated land, bulk density at

5-10cm depths had values ranging between 1.34 and 1.46 1.Mg m-3     for forest and

cultivated land respectively. Total porosity ranged from 40.77 to 46.10 % for cultivation

and forest land use while slopes have 45.00, 44.48 and 44.38 % porosity for upper,

middle and lower slopes respectively. The highest soil moisture contents at 0-5cm depth

were 4.20, 2.63 cm3/cm3 , while at 5-10cm depths values were 4.32 and 2.13 cm3/cm3

recorded under forest and cultivation land use. Middle slope shows higher soil moisture

content of 4.35 and 4.38 cm3/cm3 for 0-5 cm and 5-10 cm respectively. The pH (H2O)

ranged from 6.9 to 7.16 in the land uses. The electrical conductivity in the land uses was

0.13 dS/m and 0.12 dS/m was obtained for forest and cultivation land respectively, with

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