Electrochemical Properties of Latosols with Different Mineralogies

ABSTRACT

Studying the electrochemical behavior of colloidal particles is important for fertility management and soil conservation, since it enables the understanding of several physicochemical phenomena that occur in soils. The objective of this study was to determine the point of zero charge (PZC) and the electrochemical behavior of surface and subsurface samples of three Red-Yellow Latosols (Oxisols), with different mineralogical and textural characteristics, through potentiometric titration and ionic adsorption. The point of zero charge (PZC) and the electrochemical behavior were determined in samples from the A and B horizons of three Red-Yellow Latosols: very clayey kaolinitic (LVAcr), very clayey gibbsitic (LVAgr) and sandy loam kaolinitic (LVAcm). The analyses were conducted in soil samples with particle size smaller than 0.7 mm, with desaturation of aluminum (Al³⁺), and smaller than 2 mm, without desaturation. Solutions containing sodium (Na⁺) and nitrate (NO₃⁻) as indifferent electrolytes were used in all methods. The LVAgr, even with higher organic matter contents, had higher PZC, indicating the importance of mineralogical composition for this characteristic. Among the two kaolinitic soils, there was higher PZC in LVAcm, with lower organic matter content; however, both soils had higher PZC in the B horizon than in the A horizon. The net electrical charge estimated by the potentiometric titration method was equivalent to the net charge estimated by the ionic adsorption method for horizons A and B of LVAgr and LVAcm. At the same time, there was underestimation of the net negative charge by the potentiometric titration method for the A and B horizons of LVAcr.

KEYWORDS:

• Net negative charge
• permanent negative charge
• point of zero charge
• tropical soils

Acknowledgments

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001. We are also thankful to Fundo de Amparo à Pesquisa de Minas Gerais (FAPEMIG) and the Pós-gradução em Solos e Nutrição de Plantas (UFV).

Availability of Data and Materials

The datasets analyzed during the current study are available from the corresponding author on reasonable request.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors have no funding to report.