Planosols developed under rainfall gradient in the Brazilian semi-arid region.

The objective of this work was to evaluate the influence of the rainfall gradient on the and development of three Planosols, in diferente soil forming enviroments, in the state of Paraíba, considering three climatic subtypes according to the annual average

Caracterização morfológica de solos sódicos em diferentes paleodiques no pantanal norte.

O Pantanal é considerado a maior planície continental inundável do mundo, englobando diferentes habitats, sustentando grande diversidade vegetal e de solos, se destacando os solos sódicos (Planossolos e Luvissolos). Tais solos têm grande importância econômica, social e ambiental para a região, pois se situam em antigos diques (paleodiques) que atualmente constituem as áreas mais elevadas da paisagem sendo que a inundação dessas somente ocorre em eventos excepcionais, servindo como refúgios para animais silvestres e também para geofagia, gerando especificida de ambiental (Coelho, 2006) . Entretanto estes solos necessitam de uma melhor entendimento da relação entre seus atributos morfológicos e a ocorrência de Na+, facilitando assim o seu mapeamento. Devido à grande importância ambiental que representam estes solos, o presente trabalho visou relacionar a morfologia dos horizontes B texturais com o caráter sódico em paleodiques de diferentes estádios de dissecação dessas feições geomórficas, bem como características químicas e físicas. Observou-se que a geomorfologia guarda grande relação com a morfologia do solo, em que paleodiques mais dissecados apresentam transições irregulares, quebradas, maior porosidade e espessamento do horizonte eluvial (E)

Origin of mounds in the Pantanal wetlands: An integrated approach between geomorphology, pedogenesis, ecology and soil micromorphology.

Vegetated mounds are an important geomorphological feature of the Pantanal, where the influence of floods dictates not only hydropedological processes, but also the distribution and ecology of the flora and fauna. This work aimed to identify factors and processes that influence the formation and spatial distribution of the mounds, which are commonly associated with termite activity. In order to characterize pedological processes, macro and micro morphological descriptions, satellite image interpretation, dating of the sandy sedimentary material using OSL and carbon dating using 14C AMS were carried out. This dating of the materials indicates that the sediments in which the soils were formed were deposited during the Pleistocene, while the carbonates are from the Holocene. The basin-like format of the laminar structures suggests that part of the more clayey material was deposited in lacustrine environments. The more humid climate in the Holocene intensified argilluviation, which at an advanced stage, led to a more pronounced textural gradient, reducing drainage and leading to ferrolysis and thickening of the E horizon. Besides pedogenic processes, more erosive flooding during the Holocene began reducing and rounding the landscape's more elevated structures (paleolevees). In the final stage, these structures were occupied by termites to shelter from flooding. Thereafter, the bio-cementation action of the termite nests has increased the resistance of the vegetated mounds to processes of erosion

Micromorfologia de Plintossolos do Pantanal-MT.

Uma das classes de solos mais representativas do Pantanal Matogrossense é o Plintossolo. A interpretação das feições redoximórficas associadas a esses solos, especialmente aquelas incluídas no processo de plintização, contribuirão para o entendimento da dinâmica ambiental atual e passada, com especial ênfase na pedohidrologia. Procurou-se caracterizar micromorfologicamente 2 Plintossolos do norte do Pantanal matogrossense buscando entender os processos envolvidos na sua pedogênese. Para tanto, foram descritos e coletados dois perfis de Plintossolos Argilúvicos na RPPN SESC-Pantanal, próximo ao rio São Lourenço sob vegetação herbácea. As descrições micromorfológicas permitiram concluir que os Plintossolos estudados são poligenéticos, associados a diferentes condições hidrológics e estão possivelmente em formação, com cronologia de processos marcantes na ordem argiluviação - plintizaçã

Genesis and Classification of Sodic Soils in the Northern Pantanal.

The simultaneous occurrence of high levels of exchangeable sodium percentage (ESP) and alkalinity in soils imposes restrictions on plant development and affects physical properties such as porosity, bulk density, permeability, and hydraulic conductivity. Although sodic soils are frequent in the flood plain of the São Lourenço River, northern Pantanal, Brazil, few studies focus on their formation and classification, especially with regard to specific processes and detailed classification into lower categorical levels by the different systems available. The aim of this study was to identify the predominant pedogenetic processes occurring in sodic soils of the flood plain of the São Lourenço River to understand their genesis and assess how taxonomic classification systems contemplate the variations in soil properties. Five profiles were selected in sites with different progressive stages of dissection from erosion (P1, P2, P3, P4, and P5). At each site, a pit was dug for morphological description of the profiles and for collecting samples for chemical, particle size, mineralogical, micromorphological, and chronological analyses. Each profile was classified according to the Soil Taxonomy, World Reference Base (WRB), and Brazilian Soil Classification System (SiBCS/ Sistema Brasileiro de Classificação de Solos). Argilluviation is the predominant process, with a localized and intense ferrolysis action in the E/Bt transition zones in profile P5. Soils showed signs of lithologic discontinuity. This makes it difficult to distinguish how much of the textural gradient is inherited from fluvial sedimentation processes and how much is the result of pedogenetic processes. In the most advanced stage of alteration, P5 had a paler color, thickening of the E horizon, and an abrupt and irregular transition entering the Bt horizon in the form of a ?tongue?. When passing from the most preserved to the most eroded area, ferrolysis becomes more intense in the E/Bt transition, the electrical conductivity values decrease, and the ESP values increase, suggesting the sodification process. Under Soil Taxonomy criteria, P5 was classified as Natraqualf and the other profiles were classified as Natrudalf; under the WRB, however, all profiles were classified as Solonetz. The SiBCS exhibited variation at the Order level, with P5 classified as Planossolo and the others as Luvissolo. Despite an indication of different processes at the Order level, the SiBCS does not yet contemplate the sodic character in the studied Luvissolos. We propose inclusion of the sodic character at the Great Group level, as has already occurred with other SiBCS classes

Pedogenesis in a Pleistocene fluvial system of the Northern Pantanal ? Brazil

Sedimentology and hydrology seem to play a predominant role in soil formation in the Pantanal, since the fluvial systems of this wetland provided Quaternary sediments and shaped the landscape. However, pedogenic processes are active in this region mainly due to the floods that occur during the summer and fall season. The goal of this work was to study the pedogenesis in a representative transect on the São Lourenço fluvial fan, which has an area of about 16,000 km2 and is one of the largest sedimentary compartments of the Northern Pantanal, West Central Brazil. A transect of 125 m was studied in the late Pleistocene sedimentary lobe of the fluvial fan, where four landform elements were identified (paleo-channel, paleo-levee, paleo-floodplain and mound) and described to show the soil horizon boundaries along the landform unit. Samples were collected from trenches, auger holes, and boreholes, and were analyzed for soil description and characterization. Soil analyses carried out were: macro- and micromorphological, physical, chemical, mineralogical, C isotope fractionation, and OSL dating analyses. The set of evidence shows that the studied transect originated from Pleistocene sediments due to the activity of the São Lourenço fluvial fan. The following soil-landform element relationships developed: Quartzipsamments in the paleo-channel; Plinthaquults in the paleo-levee and paleo-floodplain and; Natrustalfs in the mound. Evidences of pedogenic processes in the transect are: a) clay eluviation and illuviation, resulting in formation of the Bt horizon in the soils at the lower part of the transect and mound; b) gleization and plinthization, mainly at the lower part of the transect, resulting in formation of mottles, reduced soil matrix, and nodules (plinthite and petroplinthite); c) bioturbation, responsible for addition of materials at the soil surface, assisting in the formation/maintenance of the mound; and d) the sodium concentration, observed in soils that have higher clay contents, which are highest in the mound has the highest levels

Genesis of textural contrasts in subsurface soil horizons in the northern Pantanal-Brazil.

O Pantanal caracteriza-se por ser uma planície inundável quaternária, com sedimentação predominantemente na forma de leques aluviais. Na evolução geomorfológica e sedimentar, é inerente a esse sistema deposicional o processo de avulsão, cuja dinâmica, associada aos fluxos de águas superficiais de cheias, impõe diferenças sedimentares importantes nessa planície. O entendimento e a diferenciação desses dois eventos podem ajudar na compreensão da variabilidade dos atributos e da distribuição dos solos associados a esses processos sedimentares. Nesse sentido, o objetivo deste trabalho foi estudar a gênese de solos do Pantanal Norte que apresentam contrastes texturais em profundidade e sua relação com a dinâmica do sistema deposicional. Quatro perfis foram estudados na região de Barão de Melgaço, MT (RPPN SESC Pantanal), dois próximos ao rio Cuiabá (AP1 e AP4) e dois próximos ao rio São Lourenço (AP10 e AP11). No AP11, os horizontes apresentam contrastes granulométricos desde a base do perfil até a superfície. No AP1, AP4 e AP10, os horizontes sobrejacentes a uma camada arenosa possuem granulometria semelhante entre si, principalmente na distribuição de areia. No primeiro caso, os fluxos de cheias, ou seja, de águas superficiais, parecem ter originado os horizontes e as camadas contrastantes na textura; no segundo, a avulsão é o processo mais evidente. Dessa forma, as duas vias podem formar solos com contrastes texturais e é possível distingui-los no campo pela morfologia, pois possuem peculiaridades que estão associadas aos processos sedimentares responsáveis pelos depósitos.201