Cemented Horizons and Hardpans in the Coastal Tablelands of Northeastern Brazil

Abstract

ABSTRACT:Horizons with varying degrees of cementation are a common feature of the soils from the coastal tablelands of Northeastern Brazil. In most cases, these horizons are represented by the following subsurface horizons: fragipan, duripan, ortstein, and placic. The aims of this study were to analyze differences regarding the development and the degree of expression of cementation in soils from the coastal tablelands of Northeastern Brazil: Planossolo Háplico (p-SX), Espodossolo Humilúvico (p-EK), Espodossolo Ferrihumilúvico (p-ESK), and Argissolo Acinzentado (p-PAC) pedons. The pedons studied displayed features related to drainage impediments. The cemented horizons from p-SX and p-EK had the same designation (Btgm), displaying a duric character that coincided with gleization features and are under podzolized horizons. In the p-ESK, the podzolization process is of such magnitude that it leads to the cementation of its own spodic horizons, which were both of the ortstein type (Bhsx and Bsm). In the p-PAC cementation is observed in two placic horizons and in the Btx/Bt horizon, as well as in the upper parts of the Bt/Btx horizon. Analysis of the micrographies from the cemented horizons showed predominance of a low porosity matrix. Such porosity is relatively greater in the horizons of "x" subscript than in the horizons with duric character. The Fe segregation lines were notable in the cemented horizons from p-EK and p-PAC, which corroborates the presence of placic horizons in such pedons. The preponderance of kaolinite in the clay fraction was widely verified in all the cemented horizons analyzed. Water immersion tests were the criteria adopted to define the duric character of the Btgm horizons from p-SX and p-EK, and in the Bsm horizon from the p-ESK. These tests were also used to confirm field morphology. In most cases, the maximum values of Fe, Al, and Si, determined by different extractions, occurred in positions overlaying the cemented horizons, whether they were spodic or not. The extracts of the aqueous solution displayed a noticeable accumulation of Si in the cemented horizons, except in the p-PAC. The presence of argillans in all cemented horizons allows them to be defined as illuvial, with the exception of the placic horizons, regardless of the presence of podzolization processes. The cemented horizons were preponderantly apedal, with a matrix of little porosity. The Fe, Al, and Si contents extracted by acid ammonium oxalate were effective at highlighting the influence of compounds with a low degree of crystallinity in the morphology of cemented horizons.

Association of Post-Barreiras and Barreiras Formation strata and influence on soil genesis, Southern Bahia – Brazil

“…The Bhm horizon of the P6 profile is formed in the contact zone (Pos-Barreiras/Barreiras Formation), and studies indicate that the difference in porosity between soil layers influences the origin of spodic horizons (Coelho et al, 2012;Gomes et al, 2017). Therefore, in the profile, the Barreiras Formation hinders the infiltration of water, and consequently, the illuviation of dissolved organic matter, favoring the formation of the Bhm spodic horizon (Figure 2e).…”

“…However, podzolization in the profile is evident by the presence of a cemented sub-horizon with a high content of OC (Table 3), and the has characteristics of ortstein (Figure 2e). Metallic compounds, especially Al levels, influence the degree of cementation (Oliveira et al, 2010;Gomes et al, 2017), and that element is high on the horizon (Table 3).…”

Carbon Stocks and Pools in Relation to the Texture of Kaolinitic Soils from the Brazilian East Coast

“…All soils have cohesive character, varying in depth and the degree of expression, mainly as a function of the texture. The CF and UF soils have a subsurface fragipan horizon and are moderately well drained, taking into consideration that the presence of cemented horizons in Tertiary soils are more common in dry summer areas (Gomes et al, 2017), such as CF and UF (Table 1). The morphological differences in depth do not influence the soil surface layer, all having a moderate A horizon and lacking redoximorphic features.…”

Sistemas pedológicos e reconstituição paleoambiental em depressões nos Tabuleiros Costeiros do Extremo Sul da Bahia

“…Vermelho-Amarelos, Plintossolos, Gleissolos, Espodossolos e Organossolos, geralmente associados a depressões em meio ao relevo predominante plano dos Tabuleiros (JACOMINE, 1996;RIBEIRO, 1998;ARAÚJO FILHO, 2003;CORREA et al, 2008;VIEIRA, 2013;GOMES et al, 2017).…”

“…os solos apresentam uma sequência lateral que passa de Latossolos ou Argissolos, para Argissolos Acizentados na borda e Espodossolos no fundo da depressão(SARCINELLI, 2010;GIMENES, 2013;GOMES et al, 2017). A vegetação predominante na área é do tipo Floresta Ombrófila Densa de Terras Baixas com enclaves de vegetação savânica de porte graminóide a arbustivo nas muçunungas.…”