Wednesday, 9 November 2005
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Atrazine Sorption in Some Selected Soils and Its Movement in a Dystrophic Red Latosol under No-Till and a Conventional Till Management Systems.

Jose M. Lima1, Sayonara A.C.M. Arantes2, Luiz A. Lima2, Luiz Roberto G. Guilherme1, and Julio C.A. Nobrega3. (1) Federal University of Lavras - UFLA/Brazil, C. Postal 37, Lavras, 37200-000, Brazil, (2) UFLA/Brazil, C. Postal 3037, Lavras, 37200-000, Brazil, (3) EPAMIG-MG/Brazil, C. Postal 3037, Lavras, 37200-000, Brazil

Atrazine (2-chlorine-4-ethylamine-6-isopropilamine-s-triazine) is one of the most used herbicides in Brazil. Its fate in the environment has been of great concern in Brazil and elsewhere. The objective of this study was to evaluate sorption and miscible displacement of atrazine in soils. Two experiments were conducted: the first one evaluated the sorption of atrazine in representative soils of the Rio das Mortes watershed, Minas Gerais State, Brazil and the second experiment evaluated sorption and miscible displacement of atrazine in soil columns with undisturbed samples of a dystrophic Red Latosol under no-till and conventional tillage systems. The partition coefficients (Kd) of the pesticides ranged from 1.34 to 5.96 L kg-1 for the soils of Rio das Mortes watershed. Sorption isotherms for dystrophic Red Latosol under different management systems were not linear for the range of atrazine concentrations used in the experiment (0; 0.125; 0.25; 0.5; 1.0; 2.5; 5.0; 10.0; 20.0; 25.0, and 30.0 mg L-1). The leaching of the molecule in dystrophic Red Latosol was slightly influenced by the management system. Soil samples under no-till systems had lower retardation factor (R=1.03) and higher hydrodynamic dispersion coefficient (D=488.97 cm2 h-1) than the samples under conventional tillage (R=1.33 and D=117.34 cm2 h-1).

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