Owing to the deficiency of farmyard manure and other organic materials, their application must be seriously restricted in most of the São Paulo's farms. The authors showed that the several soil types of the State vary widely in their need for those manures; they showed further that amongst the well drained soils, the "terra-roxa-legítima" is the one which permits the greatest restriction in their application, provided it is adequately protected against erosion and fertilized with mineral fertilizers. The reason is that, even without applications of organic manures and such as it normally presents itself in the cropped areas, the "terra-roxa-legítima" holds a fairly high content of organic matter and possesses in high grade many of the physical and physico-chemical properties which are partly conferred by the organic manures.