Characterization of physical and chemical properties of lowland soils of some states of Brazil

Abstract

Lowland ("várzea") soils in Brazil have potential to support agricultural production, but very little is known about their fertility. The presente study was undertaken to characterize the chemical and physical properties of representative lowland soils collected at 0-20, 20-40, 40-60, and 60-80 cm depth intervals from 18 sites in the states of Paraná, Minas Gerais, Rio Grande do Norte, Piauí, and Maranhão, Brazil. Organic matter contents averaged 3,4 % in the 20 cm layer of soil. Soil pH increased with depth from a mean value of 5.6 in the surface 20 cm of soil to a mean value of 6.9 in the 60-80 cm depth interval. Several soils had exchangeable Al value > 1 cmol kg^-1 Al, but soil Al saturation was generally less than 60%, level frequently associated with Al toxicity. Although base saturation was fairly low in some soils, exchangeable Ca and Mg levels were, in general, adequate throughout the profile. Extractable P, K, Zn and Cu levels were adequate in most surface soil samples, but Fe content was quite high in most of the samples analyzed. High percentage of soils in the study showed heavy texture.