Some herbicides have long persistence in the soil, which can lead to poisoning in successive crops (carryover) planted in rotation. The objective of this study was to evaluate the persistence of fomesafen in Red-Yellow Ultisol cultivated with common bean under the no-tillage and conventional systems, featuring two separate experiments. The experiments were arranged in a randomized block design with four replications arranged in a split plot, with the plots being the herbicide doses (0.0, 125, 250, 500 g ha-1) and the split-plots, the soil collection times (15, 30, 45, 60, 75, 90, 105, 120, 135, and 150 days after herbicide application). Soil samples were collected every 15 days, in the central inter-rows of the plots and transferred to 280 cm³ plastic pots, with sorghum being sown as a biological indicator of the presence of fomesafen. Plant poisoning was evaluated 21 days after emergence on a scale where 0 (zero) represents complete absence of symptoms and 100, death of the plant. Grain yield was not affected by Fomesafen doses, with no difference between treatments. The application of increasing doses of fomesafen increased the period of persistence of this herbicide in the samples. Fomesafen persistence in the soil varies according to the cropping system and the applied doses, and the safety period after its application on sensitive crops is lower under the no-tillage system.
bioassay; carryover; environmental impact
