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 + trifloxysulfuron-sodium at 0, 1, 2, 4, and 8 times the reference doses of 10, 0.112, and 7.315 + 0.185 mg dm³ 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-CO 2 evolution of 10.3% in comparison to the control. MBC and qCO2 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 qCO2. 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.
microbial biomass; phosphate solubilization; ametryn; trifloxysulfuron-sodium
