The Indian reserves are designated for the preservation of culture and population, according to the use, customs and traditions of its peoples. The experience of Guarani MBYA Indian farmers in the Boa Vista reserve in the Sertão do Promirim, was taken into consideration by the distinction of soil parameters in three agricultural environments, called yvy porã (good land, land for cultivation of "avaxi etei" = traditional corn). Field research (ethnographic and pedographic) was carried out in a submontane dense rainforest area, in Ubatuba, São Paulo State, Brazil. The soil profiles of Inceptisols and Ultisols were characterized according to morphologic, physical and chemical attributes, as well as in soil samples from the layers 0.0-0.05 and 0.05-0.10 m. The land capability of the areas was evaluated based on the Brazilian system SAAAT (evaluation system of soil suitability for agricultural use). The areas of yvy porã were identified and classified according to the agricultural potential by four Guarani Mbya key informers. Results showed that in the 0.0-0.05 m soil layer, the attributes total clay, Ca + Mg and Ca, sum of bases, base saturation, and pH defined TB3 as the soil with greatest agricultural potential. In the layer 0.05-0.10 m, the attributes were H, Ca, Al, and H + Al, total clay, CEC, sum of bases, total porosity, aggregate mean weight diameter, and pH. The principal component analysis supported the Mbya qualification of yvy porã (TB3 > TB1 > TB2), in terms of soil attributes, and also corroborated TB3 as the area of greatest agricultural potential for traditional corn. However, the Brazilian land capability system was not able to distinguish the yvy porã areas, and, due to the soil fertility factor, classified the suitability of all areas as for natural grasslands (5n). The incongruence of the interpretations of land potential substantiates the importance of traditional knowledge for the environmental and agriculture planning of Indian territory, towards to their sustainability.
ethnopedology; Guarani Mbya; local knowledge
