Pedogênese e propriedades físicas, químicas, morfológicas de solos e murundus no Médio Jequitinhonha, Minas Gerais

• Autor(a) principal: Simões, Diana Ferreira de Freitas
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1643
• topic: Murundus; Ação de Térmitas; Propriedades de solo; Matéria orgânica; Mounds; Action of termites; Soil properties; Organic matter; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

Termite mounds are soil mounds built by termites that are distributed throughout the national territory, mainly in the semiarid region of Minas Gerais. This study aimed to evaluate the physical, chemical, macro and micromorphological characteristics, and also the carbohydrates influence on the stabilization of soil aggregates in mounds. For this purpose, seven mounds soils were collected (M1, M2, M3, M4, M5, M6 and M7) along with the soil profiles without termites influence, to perform physical, chemical, micromorphological and carbohydrates analyses. Mounds soil and adjacent soil profiles presented similar textural, with a higher concentration of clay and silt in the mound central layers. In mounds soils, the formation of strong granular structure was not observed, even those originated from most weathered soils, indicating that the biological activity is not the only factor that should be considered to stabilize the structure. The principal component analysis (ACP) showed that silt, silt/clay, pH (H2O and KCl), Ca 2+, Mg 2+, S, T, V and CTCr were the main variables to differentiate the characteristics of mounds from adjacent soils. Chemicals results and ACP showed greater enrichment of available P in mound M4, indicating that the concentration of this element was performed in the past by the action of the biological activity of termites. Clay mineral fraction is dominated by kaolinite (Ct) and illite (Il) in all mounds layers and adjacent soils. There were no differences in clay mineral fraction between mounds soils and adjacent soils to the crystallinity of kaolinite. The greater cohesion observed in mound M4 probably is due to the kaolinitic clay mineralogy and low levels of iron, responsible for structural disorganization of kaolinite. Mounds soils and profiles of adjacent soils showed similarities in micropedological features and chemical composition of clay plasma, aggregates and concretions, mainly in Ca, K, Fe and Mn. Aggregates of larger diameter, obtained by mean weight diameter (DMP) and geometric mean diameter (DMG), indicated that the aggregates of larger diameter were those more stable in mounds soils and adjacent soils. The Ca2+ and Mg2+ contents were higher in termite mounds, especially in microaggregates. The greater presence of carbohydrates in termite mounds does not seem to be sufficient to promote greater aggregation to mineral particles, even if the levels of divalent cations are higher.