Abstract

The spatial soil fertility status of a 2.5 ha experimental plot was generated by mapping the soil nutrient concentration and fertility status using GIS kriging technique. The research was conducted in Mukono Zonal Agricultural Research and Development Institute, Mukono, Uganda in October 2013. Soil samples across the experimental plot were randomly taken for laboratory analysis of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and the organic matter content. The mean values of N, P, K, Ca, Mg and the organic matter content were 0.16%, 13.7 ppm, 0.44 cmol/kg, 5.35 cmol/kg, 4.83 cmol/kg and 2.78% respectively. The spatial concentration of each element and the organic matter was carried out by the interpolation technique using the 3D Analyst/Raster Interpolation/Kriging Tools while the overlay operations to generate the soil fertility map was carried out using the 3D Analyst/Raster Math Tools in ArcMap. The autocorrelation analysis was carried out using the Spatial Statistics/Spatial Autocorrelation Tools. The autocorrelation analysis indicated N, Ca, Mg and organic matter to be somewhat clustered each with the Moran’s 1 Index of 0.37, P was clustered with Moran’s 1 Index of 0.5 while potassium pattern was neither clustered nor dispersed. The spatial soil fertility pattern reflected the distribution of nutrient concentration.

Key words: Nutrient variability mapping, Kriging technique, fertility mapping.