Effects of five herbicides on activities of soil invertase and urease

The aim of this work was to evaluate the effects of five herbicides (including fomesafen, imazapic, lactofen, prometryn and thifensulfuron-methyl) on the activities of soil urease and invertase. The results showed that the invertase in soil samples treated with 0.05, 0.5 and 5 mg/kg soil of imazapic, lactofen, prometryn and thifensulfuron-methyl initially decreased, then increased and finally returned to the normal level in 3-40 d. Application of lactofen with a dose of 0.5 mg/kg tended to decrease invertase at the 3rd day, while invertase was stimulated at the 6th, 9th, 25th and 40th days. In addition, in the soil sample treated with fomesafen (0.05, 0.5 and 5 mg/kg), the invertase was significantly lower than the control group during the first 9 days, but it was stimulated at the 25th and 40th days. However, urease in the soil samples treated with imazapic and thifensulfuron-methyl (0.05, 0.5 and 5 mg/kg) and prometryn (5 mg/kg) initially decreased, then increased and decreased again. And similar effects were observed in the soil samples treated with prometryn (0.05 and 0.5 mg/kg) and lactofen (0.05 and 5 mg/kg). However, urease in these soil samples was similar with the control group at the end of the experiment. In addition, lower concentrations (0.05 and 0.5 mg/kg) of fomesafen could influence the activity of urease in a pattern of inhibition-activation, while higher concentrations (5 mg/kg) showed a pattern of inhibition-activation-inhibition.