Department of Geography

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Department of Geography

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Browsing Department of Geography by Subject "Agriculture"

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    Open Access
    Assessment of surface water quality of inland valleys for cropping in SW Nigeria
    (Appl Water Sci, 2015-07) Aboyeji, Olatunji Sunday; Ogunkoya, Olayinka
    Inland valley agro-ecosystems which are a category of wetlands have potential for sustainable crop production relative to uplands. A major challenge to their utilisation in the study area is their heterogeneity in hydrology, morphology, soil types and agro-economy. The study assessed the surface water quality of three typologies of the agro-ecosystems—amphitheatre-like valley-heads (Am), valley-side (VS), and low depression (LD)—for cropping. Surface water of six sites were sampled during the wet and dry seasons. The physicochemical properties and metal concentrations of the samples were analysed. Descriptive statistics and water quality indices were used to assess the suitability of the waters of the agro-ecosystems for cropping. Results showed that the valleys have neutral to slightly alkaline waters. Values of physicochemical parameters are generally within the acceptable range for cropping. The concentration of major cations varied across the inland valley types, but exhibited similar characteristics within each valley. The dominance of the major cations is in the order of Na [Ca [K[Mg. ANOVA results indicated that there is no significant difference in the concentration of heavy metals across the valleys (F=2.044, p=0.138, a=0.05). Generally, most of the physicochemical parameters and trace metals have low concentrations and are non-toxic to plants. Values of water quality indices (sodium adsorption ratio, soluble sodium percentage, total dissolved solids and permeability index) indicated that the concentrations of minerals in waters across the valley typologies are generally within permis- sible limits for cropping.
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    Open Access
    The Impact of Cocoa Cultivation on Soil Characterstics in Southwestern Nigeria
    (Obafemi Awolowo University, 1985) Ekanad, Olusegun; Jeje, L.K.; Adejuwon, J.O
    This study investigates the impact of cocoa cultivation on soil properties in a part of the Nigerian Cocoa Belt with a view to providing a framework for land use planning and management. For comparative purposes, the conditions under forest and fallow were also investigated. The plant-soil model was adopted in order to investigate the functional and reciprocal effects between soil and vegetation properties over time using the inferential analytical approach. This was based on the side-by-side comparison of soil and vegetation properties in cocoa and fallow plots of different ages, and in forest plots in geographically separate locations within a homogeneous zone in respect of the physical environment and landuse practices. Standard field and laboratory techniques were used to collect and analyse 15 soil and 11 vegetation parameters. The changes in, and interrelationships between soil and vegetation properties under cocoa over time viz--a-viz the situation under fallow and forest were analysed using ANOVA, 'student's t-test, Pearson' s correlation, cumulative deviations from the mean, canonical correlation and stepwise regression. The results obtained from these analyses show that: (i) the values of most soil properties are significantly lower under either cocoa or fallow than under forest while a few exhibit significant differences between cocoa and fallow; (ii} complex soil-vegetation relationships exist under cocoa as opposed to the simple situations under fallow and forest thereby indicating the disturbance of the soil-vegetation system under cocoa over time; (iii) as opposed to what obtains under forest and fallow, tree density and biomass indices under cocoa indicate deleterious effects on cocoa soils. However, foliage cover and accumulated litter indicate beneficial effects on cocoa soils over time; (iv) at about the fortieth year of cocoa cultivation the cocoa soil-vegetation system breaks down. Thus, to maintain the fertility of cocoa soils over time in the Nigerian Cocoa Belt there is the need to apply organic soil improvement techniques. For optimum land use efficiency it is recommended that moribund cocoa plots, unyielding to rehabilitating efforts, should be converted to food-crop plots t) enhance food production in Nigerian.
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    Open Access
    The Spatial Dimension in Nigerian Agricultural Development
    (Obafemi Awolowo University Press, 1977-02-22) Agbola, S. Akin
    The objectives of this augural lecture are as: to show that agriculture permeates all aspects of national life in Nigeria to an extent that only a multi-disciplinary approach can cope with its multi-faceted problems and that geography has a contribution to make to the solution of these problems; to emphasize the significance of the spatial dimension in agricultural development; to draw attention to the lack of justice done to the spatial theme in Nigerian agricultural studies; to assess geographical contributions to the spatial analysis of Nigerian agriculture, and to highlight the gaps which remain to be filled; and to suggest guidelines for space-oriented research in Nigerian agriculture.