Imazamox is an herbicide intensively used in the peanut fields of Turkey. Carbon and nitrogen mineralizations were determined at 20 degrees C to evaluate the effects of the herbicide in soils humidified to 60% and 80% of field capacity (FC) over 45 days. Three doses of this herbicide [recommended dose (RD, 10 mg kg(-1)), 2x RD, and 4x RD] were added to soils without any previous imazamox application (NI) and to peanut soils with previous applications of imazamox (I). Carbon mineralization, determined by CO2 respiration, at RD of I soil at 80% humidity was higher than that of the other herbicide doses at both 80% and 60% humidities. NO3-N contents (mg kg(-1)) of I and NI soil controls were significantly higher than with all herbicide doses at 80% and 60% of FC. Nitrate production decreased with increasing doses of herbicide and was significantly lower in I soil than NI soil at both humidity levels. It may be concluded that the presence of imazamox in both soils was negatively affected by nitrate bacteria.