Spatial Variability of Micronutrients in Termite Infested Soil Formed on Nupe Sandstone in the Guinea Savanna Region of Nigeria.

Soil micronutrients are nutrients required by plants in small quantity. They affect plant growth either directly or indirectly. Availability of these elements for crop growth and development may be affected by their distribution on the landscape. Variability in crop yield may indirectly be attributable to soil micronutrient variability. Termites have been implicated through their feeding habit, construction and repair of nest (i.e point centered pedoturbation process) for soil variability. This study therefore, assessed the influence of termite infestation on the spatial variability of iron (Fe), Zinc (Zn), copper (Cu) and manganese (Mn) in the guinea savanna region of Nigeria. These micronutrients were measured at the 0 – 15 cm depth of 20 m x 20 m grid samples in two termite infested (plots 1 and 2) and one none infested (plot 3) plots measuring 100 m x 100 m in Mokwa and Kontagora area of Niger State in Nigeria. Data collected was subjected to descriptive statistics, coefficient of variation (CV), test for normality and spatial dependence. The micronutrients were moderately variable with CV ranging from 7.5 to 33.3%, not dominated with outliers but had similar means and median. The nugget/sill ratio showed moderate spatial dependence for Fe (plot 1), Cu (plot 3) and Mn (plot 1 and 3) with range 36.4 – 73.0% for Mokwa and zero for Kontagora. Strong spatial dependence was observed in Fe (plot 1 and 3), Zn (plot 1, 2, 3), Cu (plot 1 and 2) and Mn (plot 2) in Mokwa and Fe (plots 1 and 3), Zn (plots 1, 2, and 3), Cu (plots 1 and 3) and Mn (plots 2 and 3) in Kontagora. Geostatistical analysis revealed that strong spatial dependence exists for Cu and Mn in infested plots of Mokwa, an indication that termites could be a factor in the variability of some soil micronutrients through pedoturbation.