Pedogênese e distribuição espacial dos solos da bacia hidrográfica do rio Alegre ES

• Autor(a) principal: Pacheco, Anderson Almeida
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5505
• topic: Pedogênese; Classificação de solos; Gleissolos; Pedogenesis, Soil classification; Gleysoils; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

The study area is located south of Espirito Santo. Corresponds to the river basin Alegre municipality of Alegre, a tributary of the river Itapemirim. The river basin Alegre is almost fully inserted in the broad field of "Mares de Morros" forested (rainforest). Were selected and collected 14 representative soil profiles were divided into three toposequences and extra samples: Toposequence 1 (T1) comprised two Oxisols Yellow (P1 and P2), an "Pseudogleissolo" (P3) and Haplic Gleysoil (P4), the toposequence 2 (T2) was composed by an Oxisol (P5) and Cambisol (P6); topossequence and 3 (T3) by an Oxisol (P7), a 'Pseudogleissolo "(P8) and Haplic Gleysoil (P9). Was collected two profiles Haplic Cambisols (P10 and P11), one Haplumbrept (P12), a Red (P13) and Fluvent (P14) to represent the atmosphere of these classes. Was performed semi-detailed mapping of the soils of river basin Alegre, in the scale of 1:50,000, using the method of traversal free. The area is typically small and medium farms. Except for the areas occupied by pastures and forest fragments, diversification of crops already notes: reforestation with eucalyptus (Eucalyptus spp); cultivation of peach palm (Euterpe edulis), coffee (Coffea arabica L.) is grown as a single crop, or sometimes cultivated with crops such as corn (Zea mays), beans (Phaseolus vulgaris L.) and banana (Musa spp.) mainly. The relief classes prevalent in river basin Alegre are wavy and strongly undulated, may also consider the mountain. The basin has an area of approximately 20,518.77 ha, and due to the predominance of reliefs rougher, the area has been used by family farms. In soil survey conducted, the predominant class is the Oxisol (LVAd), corresponding to more than 80% of the area. Since the total mapping unit inclusions are LVAd Ultisol, Oxisol, Cambisol and rock outcroppings. The second mapping unit higher espressividade are Haplic Cambisols (TD) with a little over 13% of the area. In mapping unit of Haplic Cambisols (CXbd1) is inclusions Oxisol and Haplic Cambisol Húmico.Os Gleissolos with mapping unit GXbd, is spatialized in the area of the river basin areas Alegre relief plan. Is this map unit inclusion of Pseudogleissolo, class is not yet defined in the Brazilian System of Soil Classification (Embrapa, 2006). This class is in a position in the landscape undulated relief, always in the sequence of a Gleysol. The Pseudogleissolo has all the characteristics of an Ultisol, but his regime is no more constant moisture, so not matching the class of Gleissolos. The contents of particle size fractions ranging from the very sandy loam clay, or clay content of 200-700 g kg-1, since the material has the granite-gneiss grained average, justifying higher levels of clay. The soils are dystrophic (V <50%), with values of sum of bases (S value), generally less than 0.5 cmolc dm-3 and low cation exchange capacity (CEC), generally less than 7.0 cmolc dm-3. These values reflect the high degree of weathering and leaching suffered. The content of Al3+ is considered high, but not enough to characterize them as alic or aluminic. The values of Kr and Ki molecular relationships ranging respectively from 0.69 to 1.48 and 0.62 to 1.43 for the subsurface horizons and from 0.86 to 1.39 and 0.71 to 1.34 for the surface horizons of the soils studied. These values indicate a high degree of weathering suffered by such materials, this feature observed in all soils. There was a tendency for higher values of the Feo / Fed in the surface horizon than in subsurface profiles of the predominant forms of crystalline iron, ie, P1, P2, P5, P6 and P7, showing the effect of organic matter in the inhibition the crystallinity of the iron oxides. This trend is no longer observed in the profiles with higher content of amorphous iron, recovered by ammonium oxalate. The XRD patterns show peaks at 0.718, 0.446, 0.358, 0.238 nm, indicating the presence of kaolinite clay mineral that prevails in the clay fraction of these soils. The presence of gibbsite identified by XRD peaks 0.485 and 0.437 nm the majority of the soil is characterized as a heavily weathered. The removal of silica and bases by percolating large amount of water, moist in a longer period, resulting in a soil solution with an ionic concentration such that the clay mineral gibbsite would be more stable. The values obtained from the crystallinity index of Hughes & Brown (1979) for kaolinite in the soils were found ranging between 9.65 and 23.16 in Oxisols, from 11.86 to 22.52 in Pseudogleissolos and Gleissolos and 16, 08 to 48.25 in Haplic Cambisols. The largest variations in micromorphological characteristics were found in the degree of development and the pedalidade micropedological features. The Oxisol (P1) showed a plasma consisting of isotropic material typical. On the horizon were observed anisotropic rare areas with weak pedalidade and microstructure composed of the strong medium subangular blocky granular. Met many micropedological features like channels and microgalerias currently filled with mineral matrix, fecal pellets termíticas with size ranging from 10 to 50 m and excremental pellets indiscriminate microarthropods. This feature is consistent with the description of the structure in the field and seems to be a common occurrence in many dystrophic Red - Yellow developed on crystalline rocks in places Seas hills of southeastern Brazil. In all soils the amounts of kaolinite were superior to gibbsite, with the exception of P10, cambisol Háplico.Mesmo so these amounts of gibbsite are considered high, since the study area is characterized as intensely weathered. The removal of silica and bases by percolation of large quantities of water in wet periods, resulting in a soil solution at a concentration such that the ionic seriously clay mineral gibbsite more stable.