Efeitos da aplicação de glifosato na química de solos alagados / Effects of glyphosate on the chemistry of flooded soils

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

10/09/2010

RESUMO

This study aimed to evaluate the effects of the herbicide glyphosate in the chemistry of the flooded soils in two humid tropical areas included in the Brazilian savanna, observing these effects in the solid fraction and the soil solution. We used soil from an area of lowland irrigated rice cultivation and a preserved area of path, constituting, respectively, a disturbed area under agriculture and a preserved area with natural vegetation. The soils were subjected to varying periods of saturation, and applying different doses of glyphosate. The treatments were: a) Dosage: Dose 0, dose 1 (1.6 mg L-1), Dose 2 (16.0 mg L-1), Dose 3 (1600.0 mg L-1) and b) periods of saturation solutions: 1, 7, 15, 30 and 60 days. The soils were previously saturated with solutions of glyphosate prepared with distilled and deionized water, and only distilled and deionized water to dose 0, for 2 hours. After that time the volume was completed with distilled deionized and deoxygenated water. At the end of each period of saturation of soil redox potential was determined in intact experimental units, as well as the pH of the solutions after separation by centrifugation. Proceeded to freezing at - 20 C of the soils and soil solutions for chemical analysis and a fraction of the solutions was wrapped and refrigerated at 4 C for later, perform the analysis of dissolved organic matter. The freezing and cooling were performed to inhibit the biological activity in the degradation of glyphosate and organic matter according to the literature. Before the analysis of the solutions we proceeded to filter membrane syringe filter to 0.45 mm in PVDF (polyvinylidene fluoride), 33 mm in diameter. Chemical analysis of soil were taken for determination of pH 0.01 M CaCl2, micronutrients (Cu, Fe, Mn and Zn), P, K, available Ca and Mg, Al, H + Al and organic matter. Chemical analysis of the solutions were limited to the determinations of Cu, Fe, Mn, Zn, K, Ca, Mg and Al and was carried out to determine the E4/E6 ratio for the humification of DOM in UV-Vis spectrometer. The different effects of glyphosate were used as the ground, showing the influence of soil characteristics and attributes in the interaction with the herbicide. The solid fraction in the analysis highlighted the effects of doses 2 and 3 in lowland soil and dose 3 in solo path. Glyphosate conferred resistance to the reduction of metals in soil and floodplain had the highest effect on the availability Eh redox sensitive elements as Fe and Mn. In the path the herbicide soil favored the reduction of metals from soil and has provided these elements. In soil solution, for the more concentrated doses, there was decreased solubilization of Fe and Mn and other elements, and affect differently the organic matter in soils, occurring in the path of higher aliphatic DOM, ie, less degradation of biological effect of dose 3. The two three doses of glyphosate and, occasionally, the first dose, influenced the chemistry of the lowland soil. The dose 3 showed more significant effects on the soil of trail. The effects of doses 1 and 2, corresponding to the doses used in the field, are highlighted as important outcomes of this study.

ASSUNTO(S)

solos úmidos solos tropicais impacto ambiental agrotóxicos poluição do solo agronomia wet soils tropical soils environmental impact pesticides soil pollution

ACESSO AO ARTIGO

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