Classification of soils on slopes of varying orientations in Umuahia area of Abia State, South Eastern Nigeria
Date
2018-10
Authors
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Publisher
Federal University of Technology, Owerri
Abstract
Slope aspect affects soil properties. The study characterized and classified soils on slopes of varying orientations in Umudike (East-lying Topo sequence) and Itu (West-lying Topo sequence), both in Olokoro Umuahia, southeastern Nigeria. Transect soil sampling technique was employed in locating three distinct positions, namely summit, midslope and foot slope along each of the topo sequences at the East and West-lying orientations. A profile pit was dug at the most representative points of the topo sequences in each of the two locations and the soil profiles were described in situ, following the FAO guidelines. Soil samples were collected from each pedon based on the horizon differentiations and subjected to routine laboratory analyses. The soils were classified using the USDA Soil Taxonomy and correlated with the FAO World Reference Base. Data obtained were subjected to statistical analysis (coefficient of variability and correlation) using the Genstat computer package. Results showed that soils of the East-lying slope were edominantly sandy-clay loam at the summit but sandy clay at the mid and foot slopes, while in the West-lying slope, the texture was dominantly sandy-clay loam at both the summit and mid slope but prominently sandy loam at the foot slope. Soils of East-lying slope had very dark grayish brown (10YR3/2) moist to strong brown (7.5YR5/8)moist, dark brown (7.5R3/2) to strong brown (7.5YR5/8) moist, dark gray (5YR4/1) to reddish yellow(7.5R6/8) moist colours at the summit, mid slope and foot slope respectively, while that of the West-lying topo sequence varied from brown (7.5YR4/2) moist to yellowish colour (5YR5/6), very dark grey (7.5YR3/1) moist to yellowish red (5YR5/8),very dark grayish brown (10YR3/2) moist to reddish yellow (5YR6/6) moist colours at the summit, midslope and foot slope, respectively. The weathering intensity of the soils varied from moderate to high with silt-clay ratios ranging from 0.04-0.93, 0.04-1.26 and 0.04-0.66 at the summit, mid slope and foot slope respectively, in the East-lying topo sequence and from 0.04-070, 0.27-1.59 and 0.14-1.08 at the summit, mid slope and foot slope respectively, i n the West-lying topo sequence. Bulk densities of soils increased with depth with mean values of 1.36 gcm-3, 1.32 g cm-3, and 1.34 g cm-3 recorded at the summit, slope and foot slope respectively, in the East-lying topo sequence and 1.37 g cm-3 , 1.33 g cm 3 and 1.32 g cm-3 at the summit, mid slope and foot slope respectively, in the West lying
topo sequence. High variation (CV>35%) was noted in Ksat in the profiles of the top sequence, with values of Ksat ranging from 0.3-1.11 cm hr-1, 0.19-1.96 cm hr-1and 0.15-1.47 cm hr-1 at the summit, midslope and foot slope, respectively in the West-lying topo sequence whereas in the xiast-lying topo sequence, the values ranged from 0.18-2 cm hr-1
, 0.11-1.97 cm hr-1and 0.12-1.48 hr-1 at the summit, mid slope and foot slope, respectively. Soil pH was very strongly acidic (4.58-4.78) in the East-lying topo sequence but varied from very strongly acidic to strongly acidic (4.52-5.30), in the west lying topo sequence. Organic matter concentration was generally higher at the epipedons and ranged from (26.44to 23.36) gkg-1 and (30.64to 18.9) gkg-1 in soils of the East-lying and West-lying slopes, respectively. Effective cation exchange capacity varied from
(8.63- 13.79) cmolkg-1 in the East-lying topo sequence and (10.42- 16.31) cmolkg-1 in the West –lying topo sequence. Soils of East-lying topo sequence were classified as Grossarenic Paleudalfs, Typic Paleudalfs and Arenic Hapludalfs Typic (USDA) at the summit, midslope and footslope, respectively and correlated with Mollic Luvisols of the World Reference Base (WRB) whereas the soils of West-lying slope were classified as Arenic Glossudalfs, Typic Paleudalfs and Typic Ferrudalfs (USDA) at the summit, midslope and footslope, respectively which correlate to Haplic Albeluvisols of the WRB (FAO) legend
Description
The thesis has tables
Keywords
Soil development, landscapes, Umuahia area, Abia State, South Eastern Nigeria
Citation
Aliba, V. O. (2018). Classification of soils on slopes of varying orientations in Umuahia area of Abia State, South Eastern Nigeria (Unpublished Masters Thesis). Federal University of Technology, Owerri, Nigeria