Atributos químicos, mineralógicos e micromorfológicos de horizontes coesos de latossolos e argissolos dos tabuleiros costeiros do estado de Alagoas

Neto, José de Almeida Lima; Ribeiro, Mateus Rosas; Corrêa, Marcelo Metri; Souza-Júnior, Valdomiro Severino de; Filho, J. C. de Araújo; Lima, José Fernando Wanderley Fernandes

doi:10.1590/s0100-06832010000200021

Cited by 23 publications

(7 citation statements)

References 30 publications

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“…Therefore, the results observed reinforce the generalized importance of Al compounds with a low degree of crystallinity in the genesis of ortstein, fragipan, and duripan horizons in coastal tableland soils (Araújo Filho, 2003;Lima Neto et al, 2010;Corrêa et al, 2015). However, they also demonstrate that Fe and Si compounds with a low degree of crystallinity also take part in the process to a varied extent, an aspect which was also pointed out by Corrêa et al (2015).…”

Section: Ph and Contents Of Fe Al And Si In Different Extractions Asupporting

confidence: 77%

Cemented Horizons and Hardpans in the Coastal Tablelands of Northeastern Brazil

Gomes

Filho

Vidal‐Torrado

et al. 2017

Rev. Bras. Ciênc. Solo

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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.

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Section: Ph and Contents Of Fe Al And Si In Different Extractions Asupporting

confidence: 77%

Cemented Horizons and Hardpans in the Coastal Tablelands of Northeastern Brazil

Gomes

Filho

Vidal‐Torrado

et al. 2017

Rev. Bras. Ciênc. Solo

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“…This disorder may be related to the high iron content in kaolinites (Lima Neto et al, 2010), given that all the soils are developed from basalt. In contrast, in all horizons with expansive capacity, the peaks at the 0.72 nm position are broad and asymmetric toward lower 2θ angles, and in the 0.36 nm position, the asymmetry is toward higher 2θ angles.…”

Section: Total Clay Fraction Mineralogymentioning

confidence: 99%

Clay Mineralogy of Brazilian Oxisols with Shrinkage Properties

Testoni

Almeida

Silva

et al. 2017

Rev. Bras. Ciênc. Solo

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Shrinkage capacity (caráter retrátil in Portuguese) is a new diagnostic characteristic recently introduced in the Brazilian System of Soil Classification (SiBCS) to indicate shrink and swell properties observed in subtropical soils from highland plateaus in southern Brazil, specifically in Oxisols with brown colors. In soils located in road cuts exposed to drying for some weeks, strong shrinkage of soil volume is observed in these soils, resulting in the formation of pronounced vertical cracks and large and very large prismatic structures, which crumble in blocks when handled. We hypothesize that such properties are related to their clay mineralogy, although there are no conclusive studies about this, the motive for the present study. Samples of the A and B horizons from six Oxisols with expansive capacity from the states of Santa Catarina and Rio Grande do Sul were analyzed. One Rhodic Hapludox, from the state of Paraná, without expansive capacity, was used for comparison. All the soils are very clayey, originated from basalt, and have similar iron oxide content. For identification of clay mineralogy, X-ray diffraction techniques were employed, together with the use of NEWMOD ® software to investigate and describe the interstratified minerals. The resultsshowed that most expansive soils have a similar mineralogical composition, with kaolinite, interstratified kaolinite-smectite (K-S), and hydroxy-Al interlayered smectites (HIS), unlike the non-expansive Rhodic Hapludox, which exhibited kaolinite with significant amounts of gibbsite and low amount of interstratified K-S. According to the mineralogical assemblage identified in the expansive soils, we can affirm that the mechanism of smectite expansion and contraction is related to the shrinkage capacity of the soil, considering that the level of hydroxy-Al intercalation is low. In addition, these mechanisms also are related to the presence of quasicrystals and domains that control the water dynamic in the smectites, contributing to shrinkage capacity.

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“…According to Kaufmann et al (2012), in typical predominant latosols of Passo Fundo, alterations on soil water availability might be intensified by a dispersion of clay on the surface. Release of clay reduces dimension of soil canaliculus by illuviation of thin particles, bringing about a sealing on soil surface (Lima Neto et al, 2010). In this particular research, soil physical attributes were not directly examined; however, the criteria established for determination of workable days employed soil hydric-physical characteristics by means of the ratio SM/SWHC, bearing in mind that such a parameter in conjunction with precipitation are responsible for substantial fluctuations in occurring probabilities of workable days as thoroughly described by Estrada et al (2015).…”

Section: Resultsmentioning

confidence: 99%

Sequence of Workable Days for Mechanized Harvest of Sugarcane in Southern Brazil

Vieira¹,

Sentelhas²,

Pereira³

2019

JAS

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The probabilities of workable days (WD), as well as probability of having a given sequence of days for sugarcane mechanized harvest in Southern Brazil is a very useful information for planning of such operation. Thus, the aim of this study was to determine the simple and conditional probabilities of WD for the abovementioned field operation in the State of São Paulo, Brazil, by means of the Markov Chain, to define the probabilities of sequences of WD. The number of WD (NWD) was determined for 32 years for ten sites using as criteria soil water holding capacity of 40 mm, rainfall ≤ 3 mm and relative soil water storage ≤ 90%. Based on NWD dataset, the simple probabilities of WD and non-workable (NW) days, as well as the conditional probabilities were determined. Finally, the probability of sequences of WD per ten-day period was obtained by the Markov chain. The results showed that Western, Northwestern and Northern, on average, were more likely to have WD compared to Southern and Eastern regions of the state. In addition, the most likely periods of WD were between April and September, being the first ten-day period of July the one with the highest possible probability (≥ 90%). The probability of having a workable day given that the previous day was workable always remained at a minimum of roughly 50% along with a maximum close to 90% at all assessed sites. Finally, the probability of a sequence of eight or more WD per ten-day period was always below 40% along the year, showing that is difficult to have such a long period available for planning sugarcane mechanized harvest in the assessed locations. Therefore, we recommend that fleets sizing should be defined as a function of NWD in conjunction with the probability of the sequence of WD at a given ten-day period.

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Atributos químicos, mineralógicos e micromorfológicos de horizontes coesos de latossolos e argissolos dos tabuleiros costeiros do estado de Alagoas

Cited by 23 publications

References 30 publications

Cemented Horizons and Hardpans in the Coastal Tablelands of Northeastern Brazil

Cemented Horizons and Hardpans in the Coastal Tablelands of Northeastern Brazil

Clay Mineralogy of Brazilian Oxisols with Shrinkage Properties

Sequence of Workable Days for Mechanized Harvest of Sugarcane in Southern Brazil

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