Use of geospatial technology in a precision soil fertility investigation of a farmland for arable crop production in a tropical environment

摘要

The Geographic Information Systems (GIS) and the Global Positioning System (GPS) were the two geospatial technologies used in a precision soil fertility investigation of a thirty five hectare farmland for arable crop production in Akure (7 degrees 15'N, 5 degrees 15'E), Nigeria. The research was carried out from January to May 2008. The latitude and longitude of the farmland were taken with the global position system receiver and the data input into the computer system. ArcView 3.3 software programme was used to generate the boundary of the farmland from the coordinates while the topographic and slope maps were generated with the elevation data. The soil fertility investigation was carried out by locating sampling pits for soil samples collection on the basis of soil slope relationship for which the entire landscape was categorized into two slope types of 0.5 to 8% and 8 to 15%. Soil samples were collected at surface (0-30 cm) and subsoil (30-100 cm) across the slopes for the soil physical and chemical properties. The average values of soil data were computed using ArcView statistical analysis tools. The results of analysis showed the soil to be sandy loam in the surface and sandy clay loam in the subsoil. The gravel content was higher in the subsoil compared to surface soil and the soil which was slightly acidic to neutral had higher organic matter, total exchangeable bases and cation exchange capacity in the surface soil compared to the subsoil. The soil fertility was adjudged to be of moderate productivity and found suitable for arable crop production but can only be sustained with addition of organic and inorganic fertilizers in a continuous cropping over the years. The application of geospatial technologies had generated a digital map of the farmland to make possible a periodic review of the fertility status.