The objective of this work was to evaluate the leaching potential and persistence of metribuzin applied in pre-emergence on samples of soils to understand the dynamics of this molecule in soils with contrasting textures. The metribuzin was applied in Red Latosol-LV (480 gha-1) and PSAMENT (360 gha-1), the experiment was conducted in green house conditions. For the leaching was used PVC columns  (30 cm long), the scheme adopted was 6 x 6 factorial with randomized blocks design with six replications, the factors studied were water blades (0, 20, 40, 60, 80 and 100 mm) and depths (0-5, 5-10, 10-15, 15-20, 20-25 and 25-30 cm) of the columns. For persistence were used plastic vases of 5 dm³, with different periods of applications distributed in randomized block design with three replications in factorial scheme 4 x 3, the factors studied  were rates (0; 480 and 360 gha-1) and the period of time between the application of the herbicide (0, 25, 50 and 75 DAA – day after application). In the assessment of percentage of control it was used as bioindicator (Cucumis sativus) for the two experiments. The metribuzin presented high leaching potential for both soils and the higher the applied water slide, greater depth achieved and efficient control of bioindicator in stricken layers. The metribuzin showed low persistence in the clay soil and sandy soil with the use of both doses. However, the persistence in the sandy soil was not influenced with the period between application and seeding of the bioindicator.

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Lixiviação e persistência do metribuzin por bioensaios

Numa serie de ensaios em laboratorio e casa-de-vegetacao, estudou-se a mobilidade e a inativacao do herbicida metribuzin em materiais de um Latossolo e de um Podzolico representativos de duas regioes do Estado de Minas Gerais, em funcao de diferentes densidades aparentes. Ensaios biologicos foram utilizados para medir a inativacao e a mobilidade do metribuzin nos diferentes solos e densidades. A densidade aparente alterou de forma pronunciada a quantidade de herbicida lixiviado atraves das colunas dos materiais dos solos estudados. Quanto maior a densidade, menor a quantidade de herbicida lixiviado. A quantidade de herbicida que permaneceu biologicamente ativo ao longo da coluna foi diretamente relacionada com a densidade, em cada solo. A mobilidade do metribuzin no material do Latossolo foi maior que no de Podzolico, em consequencia de maior atividade coloidal deste.

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L.E.F. Fontes

Papers

Movimento e inativação do metribuzin em materiais de dois solos, sob diferentes densidades aparentes