The factor scores of the PCs provide a useful method for combining information from multiple SQ
indicators providing a mean for assessing in a statistical way their spatial variation and interactive
influences on maize growth. The identified PCs (Table III) with less than 16.0% of residuals provided
a good summary of the original set of variables. The first component with high negative loadings on
exchangeable bases and positive loadings on inorganic P pools and exchangeable Al integrated mostly
soil properties related to nutrient availability and uptake. This soil quality with significant control
on biomass yield (Table II) contrasts soils with different nutrient levels and P capital as imposed by
ferrallitic pedogenesis (Tchienkoua and Zech, 2004). The lowest mean scores observed in the TKU can
be accounted for by soil age and landscape rejuvenation through erosion.