Relações solo-paisagem em uma litosseqüência arenito-basalto na região de Pereira Barreto, SP
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Data
2007-06-01
Autores
Campos, Milton César Costa
Marques Júnior, José [UNESP]
Pereira, Gener Tadeu [UNESP]
Montanari, Rafael [UNESP]
Camargo, Lívia Arantes [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Ciência do Solo
Resumo
Os objetivos deste trabalho foram estudar as relações solo-paisagem em uma litosseqüência de transição arenito-basalto e verificar a similaridade dos limites de superfícies geomórficas mapeados no campo com os limites mapeados a partir de técnicas geoestatísticas. Foi realizado o mapeamento de uma área de 530 ha, utilizando-se equipamento de GPS, e em seguida elaborou-se o Modelo de Elevação Digital, que possibilitou o estabelecimento da transeção de 2.100 m a partir do topo. Ao longo da transeção, o terreno foi estaqueado a intervalos regulares de 50 m, nos quais foram realizadas medidas da altitude para confecção do perfil altimétrico. As superfícies geomórficas foram identificadas e delimitadas conforme critérios topográficos e estratigráficos, com base em intensas investigações de campo. Coletaram-se amostras de solo em pontos laterais em 67 locais, nas superfícies geomórficas identificadas, nas profundidades de 0,0-0,25 m e 0,80-1,00 m. Além disso, foram abertas trincheiras nos segmentos de vertente inseridos nas superfícies geomórficas mapeadas. As amostras coletadas foram analisadas quanto a densidade do solo, textura, Ca2+, K+, Mg2+, SB, CTC, V, pH (água e KCl), SiO2, Al2O3 e Fe2O3 (ataque por H2SO4), óxidos de Fe livres extraído com ditionito-citrato-bicarbonato e ferro mal cristalizado extraídos com oxalato de amônio. A fração argila desferrificada foi analisada por difração de raios X. A compartimentação da paisagem em superfícies geomórficas e a identificação do material de origem mostraram-se bastante eficientes para entendimento da variação dos atributos do solo. A análise individual desses atributos por meio de estatística univariada auxiliou na discriminação das três superfícies geomórficas. O uso de técnicas de geoestatística permitiu a confirmação de que mesmo os atributos do solo apresentaram limites próximos aos das superfícies geomórficas.
The focus of our study were to study soil-landscape relationships in a sandstone-basalt transition lithosequence and to compare the limits of geomorphic surfaces mapped in the field with those mapped by geostatistical techniques. An area of 530 ha was mapped using GPS equipment in order to generate a model of digital elevation, which allowed for the establishment of a transection of 2.100 m from the hill top downwards. Along the transection, the altitude was measured at 50 m regular intervals to construct the elevation profile. The geomorphic surfaces were identified and delimited according to topographic and stratigraphic criteria based on detailed field investigations. Soil samples were collected at 67 points of the identified geomorphic surfaces, in the 0.0-0.25 m and 0.80-1.00 m depths. Besides, trenches were opened in the slope segments of the mapped geomorphic surfaces. The samples were analyzed for bulk density, texture, Ca, K, Mg, SB, CEC, V%, pH (water and KCl), SiO2, Al2O3 and Fe2O3 (H2SO4 attack), and free iron oxides extracted with dithionite-citrate-bicarbonate, while poorly crystallized iron was extracted with ammonium oxalate. The iron-free clay fraction was analyzed by x-ray diffraction. The compartmentalization of the area in geomorphic surfaces and the identification of the parent material explained well the variation in the soil attributes. An individual analysis of the soil attributes by univariate statistics contributed to the discrimination of the three geomorphic surfaces. Geostatistical techniques confirmed the agreement of the limits determined by individualized soil attributes with those of the geomorphic surfaces.
The focus of our study were to study soil-landscape relationships in a sandstone-basalt transition lithosequence and to compare the limits of geomorphic surfaces mapped in the field with those mapped by geostatistical techniques. An area of 530 ha was mapped using GPS equipment in order to generate a model of digital elevation, which allowed for the establishment of a transection of 2.100 m from the hill top downwards. Along the transection, the altitude was measured at 50 m regular intervals to construct the elevation profile. The geomorphic surfaces were identified and delimited according to topographic and stratigraphic criteria based on detailed field investigations. Soil samples were collected at 67 points of the identified geomorphic surfaces, in the 0.0-0.25 m and 0.80-1.00 m depths. Besides, trenches were opened in the slope segments of the mapped geomorphic surfaces. The samples were analyzed for bulk density, texture, Ca, K, Mg, SB, CEC, V%, pH (water and KCl), SiO2, Al2O3 and Fe2O3 (H2SO4 attack), and free iron oxides extracted with dithionite-citrate-bicarbonate, while poorly crystallized iron was extracted with ammonium oxalate. The iron-free clay fraction was analyzed by x-ray diffraction. The compartmentalization of the area in geomorphic surfaces and the identification of the parent material explained well the variation in the soil attributes. An individual analysis of the soil attributes by univariate statistics contributed to the discrimination of the three geomorphic surfaces. Geostatistical techniques confirmed the agreement of the limits determined by individualized soil attributes with those of the geomorphic surfaces.
Descrição
Palavras-chave
geomorphic surface, pedogenesis, Geomorphology, Soil attributes, Superfície geomórfica, pedogênese, Geomorfologia, Atributos do solo
Como citar
Revista Brasileira de Ciência do Solo. Sociedade Brasileira de Ciência do Solo, v. 31, n. 3, p. 519-529, 2007.