Abstract

In this study the concentrations of the atrazine, desethylatrazine (DEA), desisopropylatrazine (DIA), azoxistrobin, carbendazim, carbofuran, chlorpyrifos, diuron, endosulfan alpha and beta endosulfan sulfate, malathion, metolachlor, methomyl, monocrotofos, permethrin, profenofos, teflubenzuron, thiacloprid, tiametoxan and triflumuron were assessed in runoff water from cotton plantations under different management systems in Central-Western Brazil. The runoff water was collected from plots delimitated by steel plates, where cotton was sown under no-tillage (direct seeding) and conventional soil management systems in one farm; and no-tillage soil management systems with and without a vegetated filter strip (buffer filter) planted with Bracchiaria grass in a second farm. In general terms, there was a 51% reduction in the total mass of off-site transport of pesticides in the no-tillage system compared to the conventional tillage. In addition, when comparing the no-tillage system with conventional tillage, the pesticides: metolachlor and alfa endosulfan as well as endosulfan sulfate, its metabolite, showed the lowest reduction in relation to the other pesticides transported by runoff. Thus, these pesticides showed broad risk of contamination of surface waters. Besides, the buffer filter reduced the off-site transport of pesticides by runoff in 92%, confirming the efficiency of a Bracchiaria filter strip in the retention of pesticides carried by runoff.

Key words: Runoff water, buffer filter, direct seeding, conventional plantation system.