ABSTRACT Biolog Eco technology was used to investigate the effects of different chemical herbicide application methods, such as pre-emergence after sowing and post-emergence (stem and leaf spraying), on the characteristics of carbon source utilization by microbial communities in alfalfa rhizosphere soil. The averages of well color development (AWCD) and microbial metabolism diversity indices of post-emergence herbicide spraying on stems and leaves were significantly lower than those of pre-emergence herbicide and without herbicide treatments. Furthermore, pre-emergence after sowing herbicide treatment did […]

Glyphosate is a systemic post-emergent herbicide of the non-selective organophosphate group widely used in apple orchards in the South of Brazil. It may have adverse effects on beneficial soil microorganisms. The aim of this study was to evaluate the biodegradability of glyphosate by soil microbiota in apple orchards with different histories of application of the product. For that purpose, soil samples from the region of Vacaria, Rio Grande do Sul, were used, with the biodegradation of glyphosate being evaluated by […]

This experiment aimed at the evaluation of imazaquin sorption and transport in soils with different chemical, physical and mineralogical characteristics using batch and miscible-displacement techniques. The experiment was carried out with Neossolo Quartzarênico (RQ), Latossolo Vermelho-Amarelo (LVA) and Latossolo Vermelho distroférrico (LVdf) soils which were air-dried, passed through a 2 mm sieve and followed by chemical, physical and mineralogical characterization. A CaCl2 solution was applied in the miscible displacement experiment for the establishment of a Cl– elution curve that was used […]

The biodegradability and distribution of pesticides in the environment determine their pollution potential. The risk of contamination with atrazine herbicide was studied in an Ultisol under field conditions and complemented with a microcosm system study. This system allowed the use of 14C-atrazine under controlled conditions and to determine of the volatilization (0.33%), mineralization (0.25%) and leaching (4 to 11%) parameters, which are difficult to evaluate in the field. Ninety percent of the radioactivity remained in the soil, with 75% in […]

The aim of this study was to evaluate the sorption and desorption of imazaquin in soils with different granulometric, chemical and mineralogical characteristics. Isotherms and kinetics studies were carried out to quantify the hysteresis between sorption and desorption processes. The soils were classified as Rhodic Hapludox (LVdf), Typic Hapludox (LVA) and Typic Quartzipsamment (RQ). The soils were air-dried and passed through a 2 mm mesh sieve, and the chemical, physical and mineralogical properties characterized. The radiolabeled molecule (14C) was imazaquin, an […]

The behavior of glyphosate in a Rhodic Oxisol, collected from fields under no-till and conventional management systems in Ponta Grossa, Parana state (Brazil) was investigated. Both agricultural systems had been in production for 23 years. Glyphosate mineralization, soil-bound forms, sorption and desorption kinetics, sorption/desorption batch experiments, and soil glyphosate phythoavailability (to Panicum maximum) were determined. The mineralization experiment was set up in a completely randomized design with a 2 x 2 factorial scheme (two management systems and two 14C radiolabelled positions in the […]

The accumulation of herbicides in the environment as a consequence of their intensive usage associated to their high persistance is a matter of principal concern due to their harmful effects on the fauna and flora. Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) is one of the worldwide mostly used herbicides, and is being detected in considerable amounts in aquatic and soil ecosystems. The goal of this study was to evaluate the sorptive behaviour of atrazine in a Humic Cambisol under its natural form and in […]

Tebuthiuron adsorption was determined in samples from 0-10 to 10-20 cm layers of three soils from the county of Ribeirão Preto (SP)-Brazil: Quartzarenic Neosol (Entisol), Red Latosol dystrofic and Red Latosol dystroferric (Oxisols). Sorption data were obtained by batch equilibrium and fitted to four adsorption models: Freundlich, linear, Langmuir and Lambert. Several statistical criteria were applied for selection among these isotherms. Freundlich model showed the best fit to the data. Kd values ranged from 0.723 to 2.573 L kg-1, and […]

The soil contains a large variety of macroscopic and microscopic organisms, which compete for the available resources. Fertilizers and pesticides usually applied in soil to increase the agricultural production may determine environmental changes. Among the edaphic organisms, earthworms are outstanding for their number and role they play on soil characteristics. The performance of earthworms on the persistence, transformation and bioaccumulation of simazine was assessed in a soil treated with the herbicide. The earthworms were sensitive to simazine [CL50(14 days) of […]

Atrazine, an herbicide of the s-triazine group, was used in laboratory experiments to determine its mineralization and sorption on samples of a Dusky-Red Latosol under conventional and no-tillage systems. Atrazine ring-labeled 14C was added to the soil samples, with the 14CO2 being produced and atrazine-14C soil extracts analyzed by liquid scintillation. The results showed very low mineralization rates of atrazine, which were correlated with the total carbon and nitrogen contents, as well as with soil humic fractions. Atrazine mineralization decreased […]