Performance evaluation of selected indices of soil erodibility for Imo State soils
Date
2023-03
Authors
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Publisher
Federal University of Technology, Owerri
Abstract
This work centered on evaluating the performance of some selected indices (Clay, Modified clay ratio, Water stable aggregate, Dispersion and Erosion ratios) for determiningErodibility for Imo State soils. Soil samples were collected from 12 locations in triplicate using the completely randomized design for the selected site in Imo State. Soil physical and chemical properties determined were the particle size distribution, organic matter content, dry and bulk density, permeability, porosity and void ratio, moisture content, soil pH and specific gravity. The data obtained through field and laboratory experiments were used in measuring the indices. Soil losses were obtained from the field (insitu) using a portable rainfall simulator of 163.27mm/hr rainfall intensity. The “rainfall” was simulated under three (3) soil conditions; dry, wet and saturated. Statistical analysis using the ANOVA showed that the rainfall simulated under the conditions mentioned above were statistically significant (P<0.05). This suggests that any “rainfall” conditions chosen, can reliably produce soil losses for the study of soil erosion behavoir. The regression model equation between the soil losses and the indices of Erodibility developed showed coefficient of correlation values for Modified clay ratio – 0.7579, Clay ratio – 0.7036, Erosion ratio – 0.7279 and Dispersion ratio – 0.7056.From comparative analysis of the selected indices, it was concluded that the Modified clay ratio, Clay ratio, Dispersion ratio and Erosion ratio had performance rating between 70% and 75% probability. These four indices performed satisfactorily thereby becoming better tools in the study of erosion. Water stable aggregate is only applicable to soils having particle size above 2mm which provides for proper evaluation of the index. Overall benefit of using this indices in assessment of soil erodibility shows the unique relationship between the primary soil textural class (sand, silt, and clay) and its percentage composition which defines the true state of any soil (easily eroded or non easily eroded).
Description
This thesis is for the award of Master of Engineering (M. ENG) in Soil and Water Engineering
Keywords
Modified clay ratio, clay ratio, water stable aggregate, erosion ratio, dispersion ratio, rainfall simulation, rainfall intensity, Department of Agricultural and Bioresources Engineering
Citation
Nwachukwu, I. P. (2023). Performance evaluation of selected indices of soil erodibility for Imo State soils (Unpublished Master's Thesis). Federal University of Technology , Owerri, Nigeria