Análise de componentes principais para avaliação de resultados analíticos da fertilidade de solos do Amapá Principal components analysis for evaluation of analytical results from Amapá soil fertility

The soil study in the State of Amapa is an urgent need because it has been observed a decrease in production in that state due mainly to the rural exodus. This work was carried out with the objective of studying the soils of municipal districts of Amapa State, using collected samples in the period from 1993 to 2003. The principal component analysis (PCA) and the hierarchical classification allowed the grouping of the municipal districts of the state in four different groups, according to the similarity presented in the soil chemical properties. The low phosphorus availability, the high acidity, the high levels of exchangeable aluminum, the low sum of bases, and low values for bases saturation were the main restrictions found for the agricultural use of the soils. In the municipal districts of Cutias and Mazagao (group 1) the soil fertility was more unfavorable, while in the municipal districts of Laranjal do Jari, Macapa, Pedra Branca, Santana and Serra do Navio (group 3) and Amapa, Ferreira Gomes, Oiapoque and Vitoria do Jari (group 4) it was more favorable in relation to other groups.