Lixiviação de flazasulfuron e flumioxazin em dois diferentes latossolos

Flazasulfuron is recommended for sugarcane and flumioxazin for soybean and other leguminous crops in Brazil. Due to the importance of these crops the herbicides may be widely used and there is a need to know their behavior in the cultivated soils. In order to study the leaching of these compounds, an experiment was carried out in greenhouse with two soils: a sandy loam Typic Hapludox (LVd) with 22 g dm-3 of organic matter and a clay Rhodic Eutrudox (LRe) with 13 g.dm-3 of organic matter. Flazasulfuron was applied at 50 and 100 g.ha-1 and flumioxazin at 50 g ha-1. The soils were put in 50 cm high PVC columns, with 10 cm diameter. The herbicides were applied with a CO2 sprayer over the surface of the columns. Rains of 50 and 100 mm were dripped over the surface with perforated recipients in amounts of 10 mm each time. All treatments had four replicates. After this, the columns were cut longitudinally in halves and Cucumis sativus and Avena sativa were sown all along as test-plants. Visual evaluations of herbicide symptoms were done at 7, 11, 14 and 23 days after sowing, measuring the extent of damaged plants along the columns. Only C.sativus showed sensibility to the herbicides. Flazasulfuron at 50 g, in LRe, leached to 6,5 cm with 50 mm of rain and to 10 cm with 100 mm. In the LVd soil, it reached 3,6 cm with 50 mm and 1,1 cm with 100 mm. At 100 g, in LRe it leached 6,2 cm with 50 mm and 10,5 cm with 100 mm. In the LVd it reached no more than 2,0 cm with both rains. Flumioxazin showed very little leaching in both soils, being the symptons detected in no more than 2,7 cm in the LRe and 2,0 cm in the LVd. Symptons of the herbicides were detected in the bottom of the columns, showing that some amount was leached through the entire column of soil. The differences observed between the soils may were related to the organic mater content of the soils. Estudou-se a lixiviação dos herbicidas flazasulfuron (50 e 100 g ha-1) e flumioxazin (50 g ha-1) em um Latossolo Vermelho eutroférrico (LRe) e um Latossolo Vermelho amarelo distrófico (LVd), aplicando chuvas simuladas de 50 e 100 mm. Amostras de cada solo foram colocadas em tubos de PVC com 50 cm de altura e 10 cm de diâmetro, previamente cortados ao meio, longitudinalmente e emendados com fita adesiva. Os herbicidas foram aplicados com pulverizador de CO2 sobre a superfície dos tubos. As chuvas foram aplicadas de 10 em 10 mm, gotejados por meio de uma chapa crivada. Havia uma testemunha que apenas recebeu as chuvas e todos os tratamenos foram repetidos quatro vezes em um delineamento totalmente casualizado. Após a aplicação das chuvas os tubos foram seccionados longitudinalmente, semeando-se pepino (Cucumis sativus) e aveia (Avena sativa) ao longo dos mesmos, como plantas-teste. Aos 7, 11, 14 e 23 dias após a semeadura, foram feitas avaliações visuais de sintomas nessas plantas, registrando-se até que profundidade do perfil eram perceptíveis. Não houve nenhuma resposta com a aveia para os dois herbicidas. Flazasulfuron a 50 g ha-1 no solo LRe lixiviou até 6,5 cm com 50 mm de chuva e até 10 cm com 100 mm. No solo LVd atingiu 3,6 cm com 50 mm de chuva e detectado até 1,1 cm com 100 mm. Na dose de 100 g.ha-1, no LRe atingiu 6,2 cm com 50 mm e 10,5 cm com 100 mm. No LVd sintomas foram detectados apenas até 2,0 cm com ambas as chuvas. O flumioxazin apresentou pouca lixiviação em ambos os solos, sendo os sintomas observados apenas até 2,7 cm no LRe e, até 2,0 cm no LVd. As diferenças de lixivação observadas foram dependentes dos teores de matéria orgânica dos solos