Soil Textural Mapping: A Pathway for Sustaining Urban Agriculture in Metropolitan Lagos, Nigeria
*Ayeni, A. O. and V. T. Adedayo
Department of Geography, University of Lagos, Lagos, Nigeria
Accepted on April 19, 2012
Soil texture is one of the important factors for determining crop yields and information about agricultural viability in any geographical location. For instance, soil fertilization, soil treatment and irrigation designs as well as power requirements for farm machinery require detailed information on soil texture. This paper thus examines soil textural classes in selected urban farming areas of metropolitan Lagos, namely Tejuoso, Alapere, Festac, Barracks, Oko-Oba and Idi-Araba farm communities. It further relates the textural classifications to the cultivation and production of vegetables. Soil samples for textural analysis were collected from 6 selected locations and in each location, 5 samples at 0-15 and 15-30 cm depths were taken using composite sampling techniques. Determinations of textural classes were done in the laboratory using the mechanical analysis method with the aid of hydrometer to calculate the percentage of sand, silt, and clay in the sampled soils. The production of soil texture map was done through remotely sensed data processing. Acquired soil base map was scanned, Geo-referenced and digitized to extract the soil type layers. Updating and superimposing of attribute information of textural classification were done through interactive techniques using Microsoft excel 2007 and Arc Info version 9.2. The finding shows that the soil textural fractions (% sand, % silt, and % clay) were spatially observed, nevertheless, only one-quarter of textural classes are represented in the selected area. The regression model (R2) result generated denote P > 0.391, P > 0.100 and P > 0.529 for % sand, % clay and % silt respectively.The application of animal feed manure was noted to have contributed to high silts contents in agricultural land of urban Lagos especially around Tejuosho and Alapere areas. Litter decomposition and soil water pressure also accounted for the variability but the effect was not consistent across different soils (P < 0.06). The output of the interactive techniques also reveals that there is similarity between laboratory result and the soil map used as baseline information. Interview however reveals that farmers lack knowledge of soil map and textural classes. The study therefore recommends that for soil fertility sustainability in the urban areas of Lagos, farmers need to be enlightened on soil map, textural classes and manure application through effective education awareness.