Influence of microtopography and sampling on the variability of some chemical properties in southern Nigeria


  • A.O. Ogunkunle Department of Agronomy, University of Ibadan, Nigeria


Microtopography, Soil sampling, Soil variability, Nigeria


The variability of pH, organic C, CEC, exchangeable K, Mg, Ca and Na in two microtopographically different units within an oil palm field as estimated by two sampling teams was examined. Microtopography was found to influence the coefficients of variation (CV%) of all properties except pH. Although this effect was only significant (P<0.001) for Ca. Team estimates of variability of (CV%) within a microtopographic unit also differed. This difference was smallest of Mg (? 2%) and highest and significant (P<0.01) for K (15-33%). The degree of variability obtained is not different from that obtained by previous workers but the grouping of the properties on the bases of CV% differed from previous studies of organic C and CEC. It is concluded that areas of different microtopography should be avoided within a field, especially for experimental purposes. In addition, only one team should be involved in the soil sampling for a project unless this is impossible practically. In order that the variability grouping based on CV values may meaningful, it should specify that kind of unit (e.g. field, mapping unit, etc.), its size and the land use or management.



Research Papers