The results are given of physicochemical analyses of soils and estimated cassava yields for five production zones in Colombia. There was little correlation between yield and the factors studied. Yields tended to increase as P increased; and there was a positive response to K in 2 zones and Ca/Mg in 2 others. However, there were contradictory results with K and pH in three of the zones. Other factors affecting yield should be studied to find the reasons for this discrepancy. (CIAT
