Declining soil productivity is a major constraint to crop production in the humid tropics. This paper examines the efficiency of multiple cropping as an economic and biological method of sustaining tree crop productivity in western Nigeria. Soil characteristics under different crops and crop combinations were examined. In addition, soils under a forest in the same locality were considered as an illustration of soil quality in a condition of little or no human interference. The results show the forest unit to be the best in terms of soil quality, followed by cocoa/kola, plantain, kola, and cocoa units in that order. It is suggested that suitable combinations of tree crops can make for higher soil quality. In particular, the combination of plantain with cocoa may help to raise nutrient status, which is usually low under the latter.