The following methods of collecting soil samples for fertility studies were compared : 1) thirty individual samples covering the whole area ; 2) ten composite samples, each consisting of five individual samples, covering the whole area ; 3) five composite samples, each consisting of 20 individual samples, covering the whole area. The three types of samples were collected in each of two plots : 1) a six-hectare plot in the Estação Experimental de Ribeirão Prêto, representing the "terra roxa" soil; 2) a four-hectare plot in the Santa Maria Farm, Pindorama, where the soil is of the "arenito de Bauru" type. The pH, total carbon, and exchangeable potassium and calcium were determined in the samples. Based on data obtained in the present investigation and considering the amount of work involved in the routine laboratory tests, it is suggested that three composite samples, each consisting of 20 individual samples, are quite satisfactory for fertility studies of uniform land areas of about six hectares.