Effect of Herbicides on Soil Microbial Activity

This Work aimed to evaluate the effects of herbicides and doses on the microbial activity and inorganic phosphate solubilization potential of a soil cultivated with sugarcane. The treatments were composed by the herbicides ametryn, trifloxysulfuron-sodium, and ametryn + trifloxysutfuron-sodium at 0, 1, 2, 4, and 8 times the reference closes of 10, 0. 112, and 7.315 + 0. 185 mg dm(3) of the active ingredient, respectively. After herbicide application, soil samples were incubated for 15 days and CO2 evolution (C-CO2) was evaluated every three days. At the end of incubation, microbial biomass carbon (MBC), metabolic quotient (qCO2), phosphate solubilization potential. and relative phosphate solubilization were evaluated for the treatments tested. C-CO2 evolution was affected by the herbicides and increasing application doses. Trifloxysulfuron-sodium caused a reduction in C-CO2 evolution of 10.3% in comparison to the control. MBC and qCO(2) were negatively affected by the herbicides ametryn and trifloxysulfuron-sodium + ametryn. Trifloxysulfuron-sodium reduced MBC when applied at decreasing doses; the reverse was observed for qCO(2). Phosphate solubilization potential Was reduced with the application of ametryn (47.20%) and trifloxysulfuron-sodium + ametryn (13.55%), while trifloxysulfuron-sodium applied singly stimulated this activity in the soil (25.48%). Similar behavior was observed for relative phosphate solubilization.