Caracterização de Planossolos desenvolvidos em diferentes condições geoambientais do Estado de Pernambuco

Abstract

The Brazilian Northeast has large areas of Planosols located mainly in semi-arid region. In Pernambuco these soils occupy a good part of its territory being used mainly with livestock. Are characterized by having strong textural contrast, with indications of the contribution of transported materials and a poor drainage, there is no consensus regarding its formation. Often, there are high levels of exchangeable sodium in the Bt horizons, BC or C. In this sense, we studied four profiles Planosols located in different climatic conditions, in order to understand the processes responsible for the formation of the Bt horizon and the origin of sodium in these soils, using chemical, physical and mineralogical properties. At the end of the study concluded that the Planosols studied show features typical of its class, with no difficulties or questions for their inclusion in the criteria of the Brazilian System of Soil Classification. All soils have a strong influence of material transported in the A and E, due to the roundness of the grains in the coarse and fine sand fraction and the presence of gravel on top of the Bt horizon, but no difference was observed in the mineralogy of the profiles indicating little influence transport or intense pedogenesis. The Mg2 + are generally higher than those of Ca2 + in the soil profile. The profiles of Altinho, and Arcoverde Jataúba, have high fertility, however, the high sodium content, the imperfect drainage and drought, make these little arable land. Sodium is originated from the weathering of feldspar, found in large quantities on the horizon BC and Cr. The textural contrast between the A or E horizons and Btn are from the modification of clay minerals in situ on the horizon Btn, the transponder materials for the surface horizons of ferrolysis and Elution-illuviation of clay.