Keywords: Kerau, kriging,semivariograms, variation, vertisols, interpolation . Qiu et al [9] studied variation in the properties of a silt loam on a 10ha paddock and found that coefficient of variability of organic matter and Phosphorus where moderate (range of 16% to 33%), with both exhibiting strong spatial dependence and the Gaussian model provided the best fit for the semivariograms. Spatial distribution maps of both properties measured also showed that organic matter was low in the southwest and high in the northeast corner of the paddock while Phosphorus was high along the edges of the paddock. However, these studies were not on a vertisol. Moreover, these studies do not consider variability on smaller farms that fall within field scale of a hectare or less, typically found in Nigeria. The fact remains that the shorter the sampling range the less the variation [12]