Persistence and impact of herbicides on the soil microbiota activity in area of sugarcane

Abstract

This study aimed to evaluate the persistence and effects of the diuron + hexazinone and clomazone + ametryne herbicides on activity and microbial population in soil cultivated with sugarcane. The herbicides diuron + hexazinone (1170 + 330 g a.i ha^-1) and clomazone + ametryne (1500 + 1000 g a.i ha^-1) were applied in field in areas cultivated by sugarcane (manual crop). In intervals of 7 days after the application, up to 42 days, soil samples were collected
for the microbiologic analysis. It was verified that diuron+hexazinone and clomazone + ametrina had different effect on fungi and bacteria community. In the persistence studies the treatments constituted of applications in the field of diuron + hexazinone (1170 + 330 g a.i ha^-1), clomazone + ametryne (1500 + 1000 g a.i ha^-1) on the ground without straw cover, on the 10 t ha^-1 of sugarcane straw and on the ground and covered with 10 t ha^-1 of sugarcane  straw. The methodology used in the determination of the persistence was with bioassay, using cucumber (Cucumis sativus) and millet (Pennisetum glaucum) as bioindicators. At 60 DAT, none of the herbicides, independent of the handling of the sugarcane straw was effective in the control of the bioindicators.