Volume 34, Number 2, 2010

Regarding the difficulty of determining the inflection points in the potentiometric titration curve of humic acids by means of traditional methodologies, a Delphi program a Delphi program was developed for the multiparametric data adjustment in potentiometric titration. For this purpose, an iterative process was used, based on the Newton-Raphson method to estimate the roots of a polynomial. The humic acid potentiometric titration data, used in regressions, were obtained in an automated system of potentiometric titration. The program developed in Delphi […]

Knowledge on chemical and physical soil properties provides the theoretical basis for a sustainable planning of natural resources. This study evaluated the alteration of chemical and physical soil characteristics in a Haplustox in the Zona da Mata region of the State of Minas Gerais (Brazil), under different crop systems. The systems evaluated were orange orchards, sugar-cane plantation, pasture and forest, as control. Orange orchards and pasture had been established more than 20 years before, both in succession to sugar-cane, previously […]