In-situ soil resistivity measurements as indices for selected topsoil properties, and maize yield prediction in a basement complex terrain of Ado-Ekiti, Southwestern Nigeria.
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Date
2016
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Obafemi Awolowo University
Abstract
In-situ soil resistivity measurements and soil properties determination at two depth levels (3 cm and 50 cm) and maize tendering and yield determination were carried out at a pilot plot located within the Ekiti State University, Ado-Ekiti. This was with a view to establishing relationships between in-situ soil resistivity, soil properties and maize yield in a typical Basement Complex environment.
Wenner array platform for measuring soil resistivity at two shallow depth levels of 3 cm and 50 cm, was designed through computer modeling and field trial. Electrode spacings of 8 cm (0.08 m) and 130 cm (1.3 m) were selected for resistivity measurements at the selected depth levels respectively. The pilot plot was partitioned into 81 cells each having a dimension of 2 m by 2 m. Soil resistivity measurements were made at 729 stations at grid interval of 1 m and at the two selected depth levels. Eighty-one soil samples were collected per depth level at the midpoint of each cell. Soil properties such as moisture content, texture and pH that affect maize yield were determined for each soil sample. Maize was planted at seven hundred and twenty-nine stations, tendered to maturity and harvested for yield determination. The relationships between in-situ electrical resistivity, soil properties and maize yield were determined through descriptive statistics, cross plots, cross tabulations and spatial pattern analyses.
The resistivity of the surface layer varied between 214 and 2090 ohm-m, while that of the deeper layer varied between 284 and 1485 ohm-m. The soils at both depth levels were classified in terms of resistivity as clayey sand and sandy soil. The sandy loam and loamy sand soil textural classes were observed to be present in the surface layer and deeper layers. The moisture content of the surface layer varied between 4.11 and 12.6%, while that of the deeper layer were between 4.95 and 10.93%. Moisture content values were classified in terms of their relationships with soil texture as Plant Available Water (PAW) and Permanent Wilting Point (PWP). The pH of the surface layer ranged between 5.1 and 6.9 and the values were classified as moderately acidic, slightly acidic and neutral. The deeper layer pH values were found to be predominantly characteristic of the moderately acidic pH range. Maize yield ranged between 27 and 600 g/m and the total yield was 112.02 kg/m2. Yield values were classified as low-to-average yield and high yield. The loamy sand textural class was found to be associated mainly with the low-to-average yield category, while the high yield category was characteristic of the sandy loam textural class. Areas with relatively high resistivity were characterized by the low-to-average yield category while the relatively low resistivity zones with high yield. The moisture content regimes at both depth levels had equal cumulative relationship with maize yield. The slightly acidic pH category was prone to high yield.
The study concluded that in-situ soil resistivity could be used as index for soil properties such as texture, moisture content and pH and hence could be used as a tool for maize yield characterization.
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xx, 341p
Keywords
Plant available water, Permanent wilting point, In-situ soil resistivity, Topsoil, Maize yield prediction, Soil resistivity
Citation
Eluwole, A.B. (2016). In-situ soil resistivity measurements as indices for selected topsoil properties, and maize yield prediction in a basement complex terrain of Ado-Ekiti, Southwestern Nigeria. Obafemi Awolowo University