Resumo em Inglês:

A new method for the study of the root system of the coffee plant Coffea arabica L. is described. The method consists in excavating a ditch along a row of four plants, 15 cm apart from the trunks. Blocks of soil 30 cm square and varying thickness, depending on the depth from which they were taken, were removed so as to include a complete cross section of the root system. The first three layers were 10 cm thick; the next two layers, 20 cm; the remaining layers (variable in number), 30 cm thick. The roots from each block were washed, air dried and weighed. The data obtained were used to draw the excavation maps as represented in graphics, I, IV, VII, X and XIII. On theses maps each dot represents 0.1 g of roots. A formula is given to estimate the weight of the whole root system, from the data thus obtained. The method just described was used to study the root system of the coffee tree in four different types of soil of the State of São Paulo, Brazil. It is pointed out that the study of the root distribution based on weight alone might lead one to erroneous conclusions, since the first layers contain heavy non-absorbing roots whereas many active roots, light in weight, are located in deeper layers. A much better idea about the root distribution in the soil was obtained by drawing the excavation map on a black cloth in true seale, and then spreading the roots removed from each block soil inside the corresponding place in the map. The pictures of this arrangement are reproduced in fig. IV, V, VI, VII and VIII. The best root distribution was found in the soil "terra-roxa misturada" in the Campinas county (fig. IV). In this soil the roots extend beyond 2.5 m depth and are very' well distributed through the soil. The poorest root distribution was found in the soil "terra-roxa legítima" in the Eibeirão Preto county (fig. V). In this soil the roots are mostly confined to the superficial layers. A study of the soil profiles w r here the trees were growing offered an explanation for the configuration of the root systems; as obtained by the last method. Diagrams of the profiles are given in the text.