Point of Zero Salt Effect: Relationships with Clay Mineralogy of Representative Soils of the So Paulo State, BrazilEnglish Full Text

M. E. ALVES 1 and A. LAVORENTI2,* 2 1 Departamento de Física e Informática, Institute de Física de So Carlos-IFSC/USP, So Carlos (SP) 13560-970(Brazil). 2 Departamento de Ciências Exatas, Escola Superior de Agricultura ’Luiz de Queiroz’-ESALQ/USP, Piracicaba (SP)13419-980 (Brazil)

Abstract: The point of zero salt effect （PZSE） is the soil pH value at which the magnitude of the variable surface charges is notchanged due to variations in the ionic concentration of the soil solution. This property influences not only electrochemicalphenomena occurring at the solid-solution interface but also the flocculation degree of the soil particles. In this studywe investigated the relationships between the clay mineralogy and the PZSE values of representative soils of the S?oPaulo State, Brazil. The results confirmed the usefulness of the difference between the soil pH values measured in 1 molL-1 KCl （pHKCl） and in water for estimating the PZSE of tropical soils, except for theones rich in exchangeable Al; furthermore, the ΔpH index was highly correlated with the differencebetween the PZSE and values, reiterating the ΔpH utility for estimating both the signal and the magnitude of thenet surface charge of tropical soils. Finally, correlation and multiple regression analyses showed that the PZSE value ofweathered non-allophanic tropical soils tends to increase and to equal the soil pH due to the weathering-induced kaolinitedestabilization and concomitant Fe- and Al-oxide accumulation.

Keywords：

electrochemical properties; iron oxides; kaolinite; tropical soils; weathered soils;

Series：
(D) Agriculture
Subject：
Fundamental Science of Agriculture; Agronomy
Classification Code：
S153.6;

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Point of Zero Salt Effect: Relationships with Clay Mineralogy of Representative Soils of the So Paulo State, BrazilEnglish Full Text

M. E. ALVES 1 and A. LAVORENTI2,* 2 1 Departamento de Física e Informática, Institute de Física de So Carlos-IFSC/USP, So Carlos (SP) 13560-970(Brazil). 2 Departamento de Ciências Exatas, Escola Superior de Agricultura ’Luiz de Queiroz’-ESALQ/USP, Piracicaba (SP)13419-980 (Brazil)

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