Persistência de herbicídas em solo com cafeeiros (Coffea arábica L.)

Abstract

This research had the objective of studying oxyfluorfen, simazine+ametryn and diuron movement in soil planted with coffee (Coffea arábica L.), in Lavras-MG, Brazil. Bioassays and HPLC analysis were used to identify herbicide residues through soil profiles. The experiment was established in February 03, 1999 at "Fazenda Baunilha" in an area with 3 year old "Catuaí Vermelho" variety, planted at 3,5m between rows and 0,7m between plants in the row. The experimental design was randomized block in a 8x4x3 factorial scheme being 8 herbicide treatments, 4 depth and 3 sampling dates. The compounds and rates tested were: oxyfluorfen 480 and 1.440g/ha; simazine+ametryn 1.250+1.250 and 1.750 +1.750g/ha; ametryn 1.250 and 1.750g/ha; diuron 3.200g/ha. White oat (Avena sativa) and cucumber (Cucumis sativus) were used as test plants in the bioassays and detection by HPLC was used to identify herbicide residues in the soil. White oat performed as a good indicator plant for biological activities of simazine, ametryn and diuron but cucumber was not a good indicator of oxyfluorfen activity. Ametryn and simazine+ametryn at the highest rates (1.750g/ha and 1750+1750g/ha) showed longest biological activities among the herbicides tested and diuron the longest chemical persistence. The HPLC analysis revealed the presence of all herbicides at 145 days after applications (ÂAA.) With ametryn concentrated at 0-5cm soil layer, simazine and diuron up o5-1 cm and oxyfluorfen up to 15-40cm. The herbicide= biological activities ended at 95 d.a.a but the chemical residues of the herbicides at 145 d.a.a. indicated underwater contamination potent.al.