Sorção do Paclobutrazol em dois solos cultivados com manga irrigada

Abstract

A cinética e a isoterma de sorção do Paclobutrazol (PBZ) foram determinadas em dois solos com plantio de manga (Mangifera indica L. cv. Tommy Atkins) irrigada, sem histórico de aplicação deste produto, ou seja, um Argissolo Amarelo da estação experimental de Bebedouro, Petrolina, PE, e outro Vertissolo da estação experimental de Mandacaru, Juazeiro, BA, ambas pertencentes à EMBRA-PA Semi-Árido. Os ensaios foram realizados em laboratório a 25°C e a concentração de paclobutrazol determinada por cromatografia líquida de alta eficiência (CLAE). Para esses solos, a cinética de sorção do PBZ foi mais bem descrita com um modelo de segunda ordem e as isotermas de sorção foram lineares. Os valores de K D e K OC foram 8,8 e 7,4 cm 3 g -1 e 1275 (log(Koc) = 3,11) e 1156 (log(Koc) = 3,06) cm 3 .g -1 , respectivamente, para o Argissolo Amarelo e Vertissolo. Para dois solos, a interação do PBZ é preponderantemente com a matéria orgânica embora alguma interação com o óxido de ferro (goethita) ocorra no Argissolo Amarelo.Palavras-chave: regulador de crescimento vegetal, isoterma de adsorção, cinética de adsorção Sorption of Paclobutrazol in two soils of irrigated mango orchards AB S TR ACTThe sorption kinetics and isotherm of Paclobutrazol (PBZ) were determined in two soils from irrigated mango (Mangifera indica L. cv. Tommy Atkins) orchards with no recorded use of PBZ. An Argisol and a Vertisol respectively from Bebedouro and Mandacaru Experimental Stations of the Brazilian Organization for Agriculture and Animal Research (EMBRAPA Semi-Arid) collected in the Municipalities of Petrolina, PE, and Juazeiro, BA were used. The experiments were carried out in laboratory conditions at 25°C and PBZ concentration was determined by high performance liquid chromatography (HPLC). For both soils, the PBZ kinetic sorption was fast and best described by a second order model and the isotherms sorption were linear. The values of K D and K OC were 8.8 and 7.4 cm 3 g -1 and 1275 (log(Koc) = 3.11) and 1156 (log(Koc) = 3.06) cm 3 g -1 , for the Argisol and the Vertisol, respectively. These results show that for both soils, the reactivity of PBZ with organic matter is predominant in determining the sorption, although some interaction of PBZ with iron oxides (goethite) can take place in the Argisol.

Sulfamethoxazole sorption in eutrophic Regolithic Neosol

“…Clay minerals and soil organic matter can weakly or strongly adsorb organic molecules, depending on the sorption mechanism and on adsorbent-adsorbate interaction forces (Milfont et al, 2007). Studies conducted in soils have confirmed that SMX is adsorbed by the organic matter and minerals of the clay fraction, but not by the sand fraction and gravels composing the soil, as observed by Hou et al (2010), who demonstrated that SMX has high sorption in organic fractions (humic acids) and in mineral inorganic particles, but low sorption in the particles of the original sediments of a soil.…”