Selma Simões de Castro

Pedogênese em uma seqüência latossolo-podzólico na borda de um platô na depressão periférica paulista

A soil sequence (Oxisol → Ultisol → Alfisol) was studied on the border of a plateau, which is the oldest regional surface near the Piracicaba river valley (southeastern Brazil). Seven pits were identified, sampled and morphologically described under the different segments of the sequence (end of summit, shoulder, backslope and footslope). A bi-dimensional sketch of the soil horizons was drawn. Undeformed soil samples were taken for micromorphological studies, and mineralogical, chemical and granulometric analyses were performed. The very clayey Oxisols of the flat summit are developed on a neo-cenozoic cover and the Ultisols resulted from a lateral pedologic Latosol transformation gradually receiving at the end of the backslope a contribution from fresh siltites (Tatui formation, Permian). The genesis of the top Oxisol microaggregates is complex, but two processes became evident: the geochemical microstructure ant the zoogenetics. The Bw → Bt transition was attributed to the subsurface densification of the microaggregates due to the levelling and convexity of the original surface and to the lateral water flows growing influence downstream. Further mechanisms of argilluviation and clay destruction of the Bt horizon top by temporary hydromorphism will complete the transformation of Bw into Bt and of the latter into E, respectively.

Alteração física e morfológica em solos cultivados sob sistema tradicional de manejo

O presente trabalho foi realizado numa area agricola situada no municipio de Bariri (SP), em area cultivada com citros (Citrus sinensis), onde foram estudadas algumas alteracoes pedologicas decorrentes de um longo periodo de exploracao agricola com sistema tradicional de manejo do solo. Foi estabelecida uma condicao de sequencia topografica para que pudesse ser avaliada a importância da posicao dos solos no relevo sobre as modificacoes de alguns dos seus atributos fisicos. As observacoes foram realizadas em campo e laboratorio, em perfis verticais situados nos tercos: superior, medio e inferior da encosta em um Latossolo Vermelho com alguns atributos avaliados estatisticamente por meio de teste de comparacao de medias. Houve alteracoes na densidade do solo e da macroporosidade, principalmente nas posicoes mais baixas do relevo. Nestas posicoes, mais argilosas, ha preenchimento dos espacos vazios, com a formacao de estrutura em blocos, ocorrendo concomitantemente com a estrutura microagregada. Os tratos culturais promoveram grandes alteracoes na estrutura dos solos, mesmo em camadas relativamente profundas. O estudo ressaltou a importância de observacoes morfologicas detalhadas dos perfis de solo, em virtude da grande variabilidade dos atributos pedologicos a uma curta distância, sendo observados, num mesmo horizonte do perfil, setores compactados ao lado de bolsoes desagregados, o que atesta a necessidade de serem considerados tanto os gradientes verticais (em cada perfil) como os laterais (ao longo da topossequencia) no estudo das variacoes temporais dos parâmetros pedologicos.

Soil Erosion in Brazil from Coffee to the Present-day Soy Bean Production

Throughout the twentieth century, Brazilian agriculture was responsible for rapid occupation of territory, especially because of two major crops that were characteristic of the most important agricultural frontiers. The coffee culture was predominant in Brazil during the first half of the century. This crop greatly influenced the country’s national and international economic standing. That period was called the Brazilian coffee cycle, most notably in the south and southeast, where pedoclimatic and geomorphological conditions were more appropriate. However, during the second half of the century, soy and cattle-raising became major factors influencing the expansion of Brazilian agriculture and the incorporation of new areas to the territory, specifically in the savanna region. This expansion was the result of prevailing morphopedological conditions and the new technologies brought about by advances in agronomic research linked to soil correction, fertilization, and irrigation. Subsequent hydropedological imbalances have accelerated erosive water dissection of the relief and the consequent production of sediments, responsible for silting valley floors, reservoirs, and drainage channels. These problems are frequently caused or promoted by the intense and indiscriminate deforestation taking place, in the case of coffee, on large expanses of the Mata Atlântica (Atlantic Forest), and in the case of soy, in the savanna.

Comportamento erosivo de um sistema pedológico de Umuarama, noroeste do estado do Paraná

The town of Umuarama, Northwest of Parana, presents sandy and medium-textured soil, derived from Cretaceous Caiua Formation Sandstone. Besides the natural fragility of these soils, deforestation, use and generalized occupation have contributed to the identification of erosive processes. A slope next to the urban area was selected for a toposequence study aiming at a macro and micromorphological pedologic characterization followed by a physico-hydric characterization of the pedologic horizons. The data allowed to reach some important conclusions concerning material behavior, hydric flows, and soil erosion dynamics, making it possible to distinguish slope sections of greater or smaller erosion risks.

INDICADORES MACRO E MICROMORFOLÓGICOS DA QUALIDADE FÍSICA DE UM LATOSSOLO VERMELHO CULTIVADO COM CANA-DE-AÇÚCAR

O sudoeste do estado de Goias se destaca no processo de expansao recente do cultivo da cana-de-acucar, em especial a microrregiao de Quirinopolis, onde inicialmente foram substituidas areas de cultura anual, sobretudo soja, e em seguida areas de pastagem, sobre Latossolo Vermelho distroferrico argiloso (LVdf), que apresenta alto potencial de compactacao. O objetivo desse trabalho foi avaliar o processo de compactacao de tais solos cultivados com cana-de-acucar, considerando que os perfis selecionados foram descompactados, corrigidos e fertilizados antes do plantio da cana. Tais perfis apresentam diversas formas de usos anteriores a cana (soja/cana, pasto/cana e sucessao pasto/soja/cana), alem do manejo com e sem fertirrigacao com vinhaca, e tiveram como referencia area remanescentes de vegetacao natural. Foram avaliados indicadores macro e micromorfologicos, ensaios de resistencia mecânica a penetracao e analises fisico-hidricas em laboratorio. Os resultados indicaram compactacao superficial e subsuperficial dos perfis estudados, independente dos usos anteriores, sendo os principais indicadores a presenca de estrutura tendendo a laminar pouco porosa nos niveis compactados, alem de aumento da densidade do solo e da resistencia mecânica a penetracao.

Análise geoecológica da conservação ambiental das sub-bacias do Rio Claro (GO) e do Rio Garças (MT)

Estudos direcionados a caracterizacao de paisagens heterogeneas vem sendo favorecidos pela associacao a analise geoecologica com indices (metricas) descritores da paisagem. O objetivo do trabalho foi o de avaliar o estado de conservacao da paisagem atraves da analise da fragmentacao dos remanescentes de Cerrado nas sub-bacias do rio Claro e do rio Garcas, situadas na Alta Bacia do rio Araguaia com base em mapas de uso da terra, do ano de 2010 e calculo dos indices descritores da paisagem com uso do software FRAGSTATS. Os resultados indicam que as sub-bacias apresentam situacoes contratantes de conservacao entre as fitofisionomias e classes de uso, mas que ainda e possivel, em funcao dos resultados indicados pelas metricas de conectividade a conservacao ambiental nas areas, apos planejamentos especificos.

Infiltração da água no solo no sistema pedológico Campus do Arenito, cidade gaúcha, noroeste do estado do Paraná

Considering the importance of understanding the water status of pedological covers for studies of prevention and containment of erosive processes, this study was conducted on a slope with a pedological system composed of Red Latossol (Oxisol)/Red Argisol (Ultisol) derived from Caiua sandstone, on an experimental farm of the Universidade Estadual de Maringa, Cidade Gaucha, in Northwestern Parana State. After a detailed morphologic description of the pedologic system, infiltration experiments were carried out in the main diagnostic horizons and the respective transitions of six soil profiles along the slope. The pattern of water dynamics in the latosolic cover is different in the surface and subsurface. Over the course of time, the surface horizons AP, AB and/or BA have alternating humidity conditions, sometimes more humid and sometimes drier, according to the rain distribution and intensity. In deeper layers of the Bw horizon the water conditions depend on the vertical and lateral water movement, and are therefore not directly related to the atmospheric variations, as occur on the surface. In the podzolic cover a vertical drainage blockage was observed in the top of Bt horizon, generating above it (horizon AE) a more constantly humid zone. In general, unlike in the Latosols, humidity and dryness do not alternate in the surface horizons of the Argisol. As a result the Argisols are constantly more humid than Latosols due to lateral water flow from upslope.

Geografia e ecologia da paisagem: pontos para discussão

This paper discusses some aspects about the landscape concept and it contributions to understand the conceptual evolution of landscape according to geography and ecology. Respectively, these approaches, geographic and ecologic, emphasize the spatial analysis of landscape elements and the biological alteration and the ecological relations that are developed. Therefore, due to point view theorical and methodological, the Geoecology term has been rescued to integrate the geographic and ecological approaches. However, both approaches have used geotecnologies in identification and mapping of landscape units. Thus, it is possible to highlight that human appropriation of ecosystems is intense and transforming, therefore this factor must be considered in concept, structure and dynamic of landscapes. Keysword: landscape ecology, Geoecology, fragmentation, remnant, geotecnologies.

Influência do meio físico na produção dos assentamentos rurais das regiões do sul e do nordeste goiano

The modernization of agriculture has brought technological advances that have enabled new lands, wich were incorporated into the production system. Goias, because their edaphoclimatic and geomorphological attributes, became the target of the expansion of the agricultural frontier in the last century, especially its southern region, which quickly became agribusiness, especially in the national and international scene. However, agribusiness not substantially changed the previous land structure, unlike the model of large monoculture farms remained. Thus formed up a highly productive and competitive south, where the conditions of the physical environment were more suitable for agriculture, particularly soybeans, while the northeast, with less able land turned to extensive livestock farming. However, public policies implemented rural settlements in both regions, which differ as to size, activities and performance. The objective was to characterize the physical environment of the settlements of the two regions, in order to understand their influence on the situation of both. From the developementof cartograms showed evidence that the southern settlements are smaller and are outnumbered, but on flattened reliefs, dominated by latosoils that have good agricultural aptitude. In the other hand, the northeastern Goias settlements are larger, more frequently occur but are located on strong slopes with shallow soils and low agricultural aptitude, favoring cattle, subsistence and plant extraction.

Important factors for the dynamism of the mass movements of soil um a pedologic system of Umuarama-PR

Este trabalho foi desenvolvido no município de Umuarama, noroeste do Estado do Paraná, no compartimento geomorfológico do rio Xambrê, situado ao sudoeste do referido município. Apresenta vertentes curtas, cortadas por patamares, onde são comuns problemas de erosão, associados ao escoamento das águas pluviais, que promovem movimentos de massa do solo (deslizamentos, desmoronamentos), principalmente nas rupturas de declives. Em virtude dessa problemática, o estudo tem como objetivo identificar os fatores responsáveis pelos movimentos de massa de solo, existentes nesse compartimento geomorfológico, por meio dos resultados macro e micromorfológicos e físico-hídricos, obtidos ao longo de uma sucessão lateral de solos, representativa das vertentes e dos interflúvios da área, denominada de topossequência São José, constituída de dois conjuntos distintos de solos separados por uma ruptura de declive côncava, bem marcada. Esses dois sistemas pedológicos distribuídos, respectivamente à montante e à jusante da ruptura de declive, apresentam funcionamentos hídricos diferenciados e intimamente associados à declividade e forma da vertente, bem como à geometria e propriedades morfológicas dos horizontes dos solos dispostos vertical e lateralmente ao longo da toposseqüência, onde a referida ruptura também separa processos pedogenéticos distintos, justamente onde há a ocorrência de movimentos de massa de solo.