Chemical migration during soil water retention curve evaluation

Wetting and drying (W-D) cycles can induce important elemental migrations in soils. The main purpose of this work was to study the possible existence of soil chemical elemental migrations in samples submitted to repeated W-D cycles during evaluations of soil water retention curve (SWRC). The experimental measurements were carried out by Atomic Absorption Spectrometry (AAS) for Ca2+, Mg2+ and K+ on samples of three different Brazilian tropical soils (Geric Ferralsol, Eutric Nitosol and Rhodic Ferralsol). Results demonstrate an increase in the electrical conductivity of the water extracted from the samples and significant losses of Ca2+, Mg2+ and K+ during the applications of up to nine W-D cycles. It was also observed differences in SWRC for all soils when samples submitted to the application of several W-D cycles were compared with samples not submitted to it. These differences occurred at the region of both structural and textural pores. A possible explanation for these results could be the soil chemical migration during the sequences of W-D cycles, which can affect the soil structure development.

Os ciclos de umedecimento e secamento (U-S) podem induzir importantes migrações de elementos químicos no solo. O objetivo principal deste trabalho foi estudar a possível existência de migração de elementos químicos em amostras de solos submetidas a repetidos ciclos de U-S durante a avaliação da curva de retenção de água do solo. As determinações de Ca2+,Mg2+ e K+ foram obtidas por Espectrometria de Absorção Atômica em três diferentes solos tropicais do Brasil (Latossolo Vermelho-Amarelo, Nitossolo Vermelho e Latossolo Vermelho). Os resultados demonstram um aumento da condutividade elétrica da água extraída das amostras de solo e perda significativa de Ca2+, Mg2+ e K+ após a aplicação de nove ciclos de U-S. Diferenças nas curvas de retenção foram também observadas para todos os solos quando as amostras submetidas aos ciclos de U-S foram comparadas com as amostras não submetidas. Essas diferenças ocorreram tanto na região estrutural quanto textural dos poros do solo. Uma possível explicação para esses resultados pode ser a migração de elementos químicos do solo durante as sequências de ciclos de U-S, os quais podem afetar o desenvolvimento da estrutura do solo.

Chemical migration during soil water retention curve evaluation.

Wetting and drying (W-D) cycles can induce important elemental migrations in soils. The main purpose of this work was to study the possible existence of soil chemical elemental migrations in samples submitted to repeated W-D cycles during evaluations of soil water retention curve (SWRC). The experimental measurements were carried out by Atomic Absorption Spectrometry (AAS) for Ca(2+), Mg(2+) and K(+) on samples of three different Brazilian tropical soils (Geric Ferralsol, Eutric Nitosol and Rhodic Ferralsol). Results demonstrate an increase in the electrical conductivity of the water extracted from the samples and significant losses of Ca(2+), Mg(2+) and K(+) during the applications of up to nine W-D cycles. It was also observed differences in SWRC for all soils when samples submitted to the application of several W-D cycles were compared with samples not submitted to it. These differences occurred at the region of both structural and textural pores. A possible explanation for these results could be the soil chemical migration during the sequences of W-D cycles, which can affect the soil structure development.