The aim of this study was to evaluate the leaching of the herbicides metolachlor and fomesafen in an Alfisol soil trough irrigation water under no-till and conventional tillage systems. One experiment consisted of three replications with metolachlor (2,4 kg ha-1) applied in pre-emergence, at water depths of 5, 10 and 15 mm, and fomesafen (0,225 kg ha¹) applied in post-emergence, at water depths of 3, 6 and 9 mm. The herbicides had also been applied by spraying. Bioassays were carried out under greenhouse conditions using soil samples from the plots. The soil samples were taken each fifteen days from layers of 05, 5-10 and 10-15 cm depth. The first sample, out of a total of four, was collected 15 days after herbicides aplication. The samples were sowed with sorghum bicolor, hybrid BR 304, which was used as test-plant. Fifteen days after sowing, the whole plants (shoot and roots) were collected for dry mass weight. Under no-till, metolachlor was not detected in the soil at 15 days after aplication, regardless of the application method. Under the conventional system, only metolachlor herbigation affected sorghum growth at the 0-5 cm soil layer. Fomesafen was leached down to 10 cm depth, being detected at the last sampling date (60 days after application), regardless of the application methods. Herbigation of metolachlor and fomesafen showed to be reliable in relation to soil movement.
herbigation; metolachlor; fomesafen; tillage systems
