Caracterização de neossolos regolíticos da região semi-árida do Estado de Pernambuco

Abstract

The Brazilian semi-arid region is characterized by high temperatures and seasonal rains, all saw, there is in their areas, large areas of cultivation that support a primarily family farms, often subsistence. The full cultivation in this region is limited by semi-dry phenomenon that provides, among other things, the development of generally less evolved soils such as Regolithic Neosols. This soil class, however, presents a reasonable agricultural potential due to the significant presence of easily alterable minerals in your mineralogical assembly. In the face of climate and soil singularities, outlined above, this study aimed to study the genesis and its implications on the properties, the potential and the limitations of agricultural Neossolos Regolíticos in Pernambuco semiarid. The morphological characterizations, physical, chemical, mineralogical and petrographic five soil profiles from granitoids and gneisses in the municipalities of São Caetano (P1), Golden Pond (P2), Caetés (P3), St. John (P4) and Parnamirim ( P5) along the rough and State hinterland point to the existence of similar soils and small degree of pedogenetic development, namely, from medium to very deep and sequence of horizons a-AC-Cr. The five soils are sandy or medium texture and well drained. The profiles of São Caetano and Parnamirim are presented solódicos in depth, however, all soils have low levels of organic matter and plant nutrients such as the phosphorus. Mineralogical the Regolíticos Neossolos studied show predominance of quartz followed by economic and feldspar. In fact the high presence of mica and feldspar on the local conditions favor the action of neoformadores processes monosialitization in all profiles. It was also found the bissialitização process at Golden Pond profile. These processes result respectively in the formation of kaolinite and smectite minerals group of. There was, in Golden Pond, the presence of smectite with isomorphic substitution of silicon tetrahedral chain of iron and / or aluminum, probably beidelita / nontronite. With the results we can conclude that climate is the main limiting factor of Neossolos Regolíticos studied, and its variation between the five profiles do not promote broad differentiation of morphological attributes, physical, chemical and mineralogical. However, the atmosphere coupled with good drainage, in most soils, provide an neoformador environment with the consequent formation of kaolinite. The position in the relief of Golden Pond profile contributes to the neogenesis of smectite rich in naturally no elements found in abundance in the exchangeable phase of these soils. All via the attributes studied did not indicate major limitations of use, suggesting a moderate agricultural potential soils. All via the attributes studied did not indicate major limitations of use, suggesting a moderate agricultural potential soils.