Laboratory simulations were used to study the potential influence of bases (K+, Mg++, Ca++) reaching soil via the burning of natural vegation—a common practice of shifting agriculture—on the genesis of argillic horizons and the evolution of Oxisols to Ultisols on the plateaus of Cabo Delgado (NE Mozambique). The effect of such a practice on the gradual enrichment with sand of the soils on slopes and in the bottom of valleys and dambos imbedded in the plateaus was also examined. The results suggested that the burning of natural vegetation before the establishment of shifting agriculture on plateaus in the province of Cabo Delgado causes the pH of the topmost soil layer to rise and facilitates its disaggregation. This, in turn, results in clay illuviation to subsurface horizons, as well as the erosion of fine sand by runoff water and its accumulation on slopes and in valley bottoms, all of which will have major implications on soil morphology and evolution.