Crop yield potential as telltale indice of soil weathering extent and fertility status: The case of East African Highland Bananas

In the African Great Lakes Region, bananas are grown on a diversity of soils with different weathering stages. However studies using the crop yield potential as a mean of soil weathering degree assessment are still scanty. Bananas were grown on five soils types to test if such a relationship could be ascertained. Mineralogical composition, elemental total analysis, routine chemical analysis, oxalates and dithionite-citrate-bicarbonate (DCB) extractions on the 0-20 and 20-40 cm soil layers were used as soil characteristics. Banana yield was higher in Cibitoke where the soil was characterized with relatively high values of total reserves in bases (TRB) and the weathering index of Parker (WIP). In contrast, no yield was recorded in Gitega where the soil had relatively lower values of TRB and WIP and high Fe DCB/Fe total ratio. Furthermore, banana yield was strongly and significantly (p<0.05) correlated with the TRB, the mineral reserves, Fe oxalate/Fe DCB ratio, the silt content and poorly correlated with the soil pH, total carbon and nitrogen, available P, exchangeable bases and the CEC. It was concluded that banana yield potential reflected well the soil weathering extent and in complement to soil properties related the routine analysis, the total analysis provide even more precision to elucidate the snapshot of the soil properties in the light of the observed banana yield potential.