In order to determine the most economical and efficient physical and chemical soil treatments for the best agricultural production according with local conditions and necessities of crops, field and laboratory works were made in conformity to the methods used by the Soil Department of this Institute. The region studied includes about 10 Km² of poor sandy soils, situated in a zone between two geological formations, soils which till the present have been poorly known. The crop is tung-oil tree (Aleurites jordii Hems ley). In the related and discussed analytical data for the present not very much in use in Brazil, but which play a part in modem pedological practice, are to be mentioned : water soluble elements, exchangeable bases, several kinds of acidity, total colloidal-matter elements ; SiO², Al²O³ and Fe²O³ of colloidal complex, and several indexes concerned with vegetable life ; porosity, higroscopicity and different moisture data ; soil air, mechanical analysis with and without peptization, dispersibility of colloid content, resistance against erosion, capillarity potencial, mean pore diameter, permeability and capillar ascension of water; mineralogical analysis of soil, parent material study and roentgenograms, viz., pictures of reflexion X-rays bands dues to interference with crystalline structure of soil clays. Each one of the genetic horizons, in which the soil profiles (taken as far as two meters in average) were divided, was analysed separately. All data were expressed for volume of soil. Pore spaces and water content are referred to natural, maximum and minimum conditions. The results of physical and chemical analysis were also presented by mean of volumetric diagrams and compared with correspondent data of six of the most important soil types of the State of São Paulo. Notes about geology, soil types variation according to topographical conditions, calculated normal climatologic data for the farm, hytherographic diagram of Knoche and notes about vegetation were presented. After mentioning the injurious and unfavourable soil conditions, some mesures and experiments are suggested in the endeavour to improve economically the yield in the studied soil. Some notes about the quantity of fertilizers to be used in soils in general were given.