Abstract:Hardening and stability of plinthic materials of the Araguaia River floodplain under different drying treatments. Rev Bras Cienc Solo. 2018;42:e0170190.
“…The great variability in compressive strength between immersion periods is related to the great natural variability observed in the composition of subsamples from a same soil horizon and to the impossibility of selecting subsamples with the same degree of purity because of their different stages of development, consistent with observations by Santos and Batista (1996) and Martins et al (2018). However, Alexander and Cady (1962) and Daugherty and Arnould (1982) claimed that the conditions required for the hardening of plinthic materials are extremely variable, particularly the amount of time required, in disagreement with the results of this study.…”
Section: Compressive Strength Of Plinthite and Petroplinthite Under Dsupporting
confidence: 85%
“…In ferruginous materials, Santos and Batista (1996) found values that allow concluding that the compressive strength applied to the plinthites of this study reflect a negative association between the most crystalline Fe forms and the hardening degree of these structures. Similarity, Martins et al (2018) verified a strong correlation between the Fe contents and the compressive strength applied in plinthite samples of soil profiles of the Araguaia river floodplain. (1) The stability of plinthite and petroplinthite subsamples was analyzed through wet sieving on a Yoder shaker apparatus (Donagema et al, 2011).…”
Section: Compressive Strength Of Plinthite and Petroplinthite Under Dsupporting
ABSTRACT:Although ferruginous materials occur frequently in soils of tropical regions, information about the reversal of the hardening process of these materials is scarce. This study assessed the influence of different chemical treatments and periods of immersion on the reversibility of the hardening process of plinthite and petroplinthite in soils of the Araguaia River plain. Soil samples were collected from the plinthic horizons in 0.10 m high and 0.15 m diameter PVC cylinders and divided into subsamples with a rock hammer. Homogeneous petroplinthite samples were also collected and broken into subsamples with a rock hammer. The plinthite and petroplinthite subsamples were subjected to five immersion treatments: distilled water, calcium carbonate solution, sodium hydroxide solution, sodium hydroxide solution + sodium hexametaphosphate, and acidic solution. The subsamples were immersed for 20, 40, 80, and 160 days. The dispersion and stability degrees and compressive strength in these subsamples were assessed. The wet aggregate stability test indicated no impact on the structural stability of plinthite and petroplinthite subsamples subjected to the treatment with different chemical agents, demonstrating the non-reversibility of the hardening process of these materials of the Araguaia River floodplain, under the studied conditions.
“…The great variability in compressive strength between immersion periods is related to the great natural variability observed in the composition of subsamples from a same soil horizon and to the impossibility of selecting subsamples with the same degree of purity because of their different stages of development, consistent with observations by Santos and Batista (1996) and Martins et al (2018). However, Alexander and Cady (1962) and Daugherty and Arnould (1982) claimed that the conditions required for the hardening of plinthic materials are extremely variable, particularly the amount of time required, in disagreement with the results of this study.…”
Section: Compressive Strength Of Plinthite and Petroplinthite Under Dsupporting
confidence: 85%
“…In ferruginous materials, Santos and Batista (1996) found values that allow concluding that the compressive strength applied to the plinthites of this study reflect a negative association between the most crystalline Fe forms and the hardening degree of these structures. Similarity, Martins et al (2018) verified a strong correlation between the Fe contents and the compressive strength applied in plinthite samples of soil profiles of the Araguaia river floodplain. (1) The stability of plinthite and petroplinthite subsamples was analyzed through wet sieving on a Yoder shaker apparatus (Donagema et al, 2011).…”
Section: Compressive Strength Of Plinthite and Petroplinthite Under Dsupporting
ABSTRACT:Although ferruginous materials occur frequently in soils of tropical regions, information about the reversal of the hardening process of these materials is scarce. This study assessed the influence of different chemical treatments and periods of immersion on the reversibility of the hardening process of plinthite and petroplinthite in soils of the Araguaia River plain. Soil samples were collected from the plinthic horizons in 0.10 m high and 0.15 m diameter PVC cylinders and divided into subsamples with a rock hammer. Homogeneous petroplinthite samples were also collected and broken into subsamples with a rock hammer. The plinthite and petroplinthite subsamples were subjected to five immersion treatments: distilled water, calcium carbonate solution, sodium hydroxide solution, sodium hydroxide solution + sodium hexametaphosphate, and acidic solution. The subsamples were immersed for 20, 40, 80, and 160 days. The dispersion and stability degrees and compressive strength in these subsamples were assessed. The wet aggregate stability test indicated no impact on the structural stability of plinthite and petroplinthite subsamples subjected to the treatment with different chemical agents, demonstrating the non-reversibility of the hardening process of these materials of the Araguaia River floodplain, under the studied conditions.
“…The pasture areas tend to be established in the more rugged regions, or with less developed soils from a genetic point of view (OLIVEIRA, 2014). Pasture areas tend to be mainly concentrated in the Araguaia Valley region, notable for its Plintosols (MARTINS et al, 2017) with livestock farming, while in the central areas towards the south and east, for example, highlighting dairy basins located in municipalities such as Piracanjuba, Bela Vista and Morrinhos (FERREIRA et al, 2019). The land use and cover conversions in the state of Goiás corresponded to 27% of the cover between the years 1985-2000, and to 25% in the years 2000-2018, with this deforestation being detected as a potentiator of soil losses, with emphasis on the Boa Vista and Bonito river basins, both tributaries of the Caiapó river, which present extensive areas with Quartzarenic Neosols and Latosols of medium texture.…”
A perda de solos depende de fatores naturais e antrópicos com elevada variabilidade espacial e temporal que podem ser inferidos por modelos de predição como a Equação Universal de Perda de Solos Revisada (EUPS-M). Nesse sentido, o objetivo deste trabalho é analisar a distribuição e a variação espaço-temporais das perdas de solo no estado de Goiás para os anos de 1985, 2000 e 2018, a partir da aplicação da EUPS-M, tendo a bacia hidrográfica como unidade de análise multiescalar. Os resultados demonstram que, em geral, há o aumento na perda média de solos no estado entre os anos observados, sendo que, em 1985 a média foi 2,4 ton.ha-1.ano-1, crescendo para 10,8 ton.ha-1.ano-1 no ano de 2000 e 11,56 ton.ha-1.ano-1 em 2018. As regiões hidrográficas do Tocantins e do Paraná são as que apresentam maiores perdas. Para além do controle geral da expansão da conversão dos Cerrados, o estado de Goiás apresenta dois padrões espaciais de perda de solos, um no qual predomina o controle dos fatores naturais, ligados aos aspectos morfogenéticos com forte influência do fator topográfico e o outro da erosividade das chuvas, espacializadas em áreas como o “front” da cuesta Caiapó, a Serra Dourada e a Serra dos Pireneus. Esses dois fatores, quando associados definem áreas sensíveis, com as maiores perdas de solo do estado de Goiás.
“…Jacomine et al (2010) carried out tests to confirm the presence of plinthites in soil samples, based on wetting and drying cycles of the samples and their resistance to crumbling and hardening, also used by Almeida and Santos (2021). The stability of plinthites after different drying methods was evaluated by Martins et al (2018). All the studies reaffirm the interpretative difficulty of the data obtained, as well as the high variation of the results.…”
Soils classified as Alisols are very frequent in the sedimentary agricultural areas of southern Brazil. The presence of red mottles with morphology similar to plinthite and saprolite residue is very common in these soils, and its identification can be considered a difficult task, both in the field and in the laboratory. The incorrect identification of these redoximorphic features can affect soils' taxonomic and technical classification. We aimed to compare morphological, physical, chemical and mineralogical data to identify reddish mottles, possibly plinthites or saprolite residues, that occur in soils with high textural contrast in southern Brazil. Four soil profiles classified as Argissolos Bruno-Acinzentados (Alisols) were sampled. Matrix and mottles samples from the horizon Bt, CB, C and Cr were separated and subjected to morphological, granulometric, total sand fractionation, chemical extractions of iron and potassium and mineralogical features. Peds from each horizon were submitted to the submersion test in water for 2 and 8 hours and to 5 wetting and drying cycles. The mineralogy indicated the low degree of alteration of the samples, with abundant presence of 2:1 minerals and feldspars, even in the clay fraction. The saprolite resisted in the water submersion tests, making it difficult to interpret the results for the correct identification between plinthites and saprolite fragments. The morphological field data associated with the results of the tests of submersion in water, the cycle of wetting and drying, the dissolution of K and mineralogy, indicate the saprolithic nature of the mottles in all horizons and profiles. The submersion test in water for 2 and 8 hours was not efficient for the plinthite/saprolite identification. The cycle of wetting and drying tests allowed the identification of saprolite.
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