Sorção e dessorção de tiametoxam e atrazina em solo sob diferentes sistemas de manejo

Abstract

A sorção e dessorção de agrotóxicos no solo são fatores importantes que contribuem para o processo de retenção, bem como seu destino ambiental e biodisponibilidade. Objetivouse avaliar a sorção e a dessorção do tiametoxam e atrazina em um Latossolo Vermelho distroférrico típico submetido a diferentes sistemas de manejo em um experimento de longa duração. Os sistemas de manejo do solo avaliados foram convencional, integração lavoura pecuária e plantio direto. Para tal, utilizou-se o método da batelada além de amostras de solo coletadas nas profundidades de 0-10 e 10-30 cm. Observou-se baixa retenção de ambos os agrotóxicos no solo para os sistemas de manejo. Para sorção, considerando ambas as profundidades e todos os sistemas, os valores dos coeficientes de Freundlich variaram de 0,87 a 4,30 L kg -1 para o tiametoxam e de 0,98 a 3,55 L kg -1 para a atrazina. Os expoentes de Freundlich variaram de 0,53 a 1,70 para ambos os compostos considerando-se todas as profundidades e sistemas. Os coeficientes de dessorção foram, em sua maioria, superiores aos de sorção sugerindo a ocorrência do fenômeno de histerese. Sorption and desorption of thiamethoxam and atrazine in soil under different management systems A B S T R A C TSorption and desorption of pesticides are important factors that contribute to retention process as well as their environmental fate and bioavailability. This study had the aim to evaluate sorption and desorption of thiamethoxam and atrazine in a typical distroferric Red Latossol under different management systems in a long-term field experiment. The evaluated soil management systems were conventional, integration of crop-livestock and no-tillage. To do so, batch equilibration method was used and soil samples were collected at 0-10 and 10-30 cm depth. In general, a low retention was observed for both pesticides in soil for all management systems. For sorption and considering both depths and all systems, the values of Freundlich coefficients ranged from 0.87 to 4.30 L kg -1 for thiamethoxam and from 0.98 to 3.55 L kg -1 for atrazine. Freundlich exponents ranged from 0.53 to 1.70 for both pesticides considering all depths and management systems. Desorption coefficients were mostly greater than sorption coefficients, which suggests the occurrence of hysteresis.

Use of Lysimeters to Evaluate the Atrazine Dynamics in Soil Cultivated With Maize

“…According to Dores [23] in a study conducted in oxisols, triazines have great potential for contamination of groundwater and surface due to their high solubility, persistence in the environment and low adsorption to soil. In a study carried out by Schimidt [24] the sorption and desorption of thiamethoxam and atrazine were evaluated in different management systems, using the experiment in a soil classified in clay dystroferric Red Latosol, which predominates clay in its constituents.…”

Microbial Activity of a Plinthosol With Application of Thiamethoxam Insecticide and Biochar

“…In addition, although the biochar presents high molecular stability, after its application to the soil, processes of oxidation of the aromatic structures forming new electric charges and reactive functional clusters in the soil occur (Petter et al, 2017). This higher reactivity may represent an improvement in the retention of molecules as it occurs in organic matter (Schmidt et al, 2015).…”