Summary
This paper describes six soils which occur along the Transamazon Highway, in a segment of 31,4 Km, between the igarapé Vermelho and the rio Cajazeira, located in the left side of the Tocantins River watershed, Itupiranga Municipality. Pará State. The soil orders found were: Entisol. Oxisol and Ultisol, which correspond to Solos Pouco Desenvolvidos, Latossolos and Podzolico Vermelho Amarelo in the Brazilian System of Soil Classification. In the area studied, Oxisol (65%) predominated, followed by Entisol (22%) and finally Ultisols (13%). The exploratory soils map by PROJETO RADAM (1974) assigns for this area a predominance of Ultisols over Oxlsols. Despite the considerable difference in scale (RADAM, 1:100,0000. while in this paper. 1:10,000), there is good agreement in the soil units present. As one would expect from the generalizations implicit in the exploratory map of RADAM, there is disagreement concerning the soil predominance in the area under consideration. The soil moisture regime is ustic and the soil temperature regime is isohyperthermic. The results obtained on water balance of these soils suggests a considerable loss of rain water through surface flow which is especially high during 3-5 months of the year. When dealing with soils of moderate permeability like those studied here, it is recommended that erosion-control measures be adopted prior to implementation of short or long-term agricultural activities.