Effects of Imazamox on Soil Carbon and Nitrogen Mineralization under Two Different Humidity Conditions

Abstract

Imazamox, is a herbicide intensively used in the peanut field soils of Osmaniye, Turkey with Mediterranean climate conditions. In this study, two types of soils were selected, first not exposed (NE) to Imazamox previously and the second Imazamox treated peanut soil (P). The recommended field dose [(RFD), 40 g L-1 active ingredient], 2 x RFD, and 4 x RFD of this herbicide were added to the NE and P soil. The microbial activities of the soils were measured by carbon and nitrogen mineralization under two different humidity conditions [60% and 80% of field capacity (FC)]. Carbon mineralization was determined by the CO2 respiration method at 30 C over 45 days. Mineralization ratios (%) of carbon in all herbicide doses of P humidified at 60% and 80% PC were significantly higher than all the other dose humidity combinations of NE soils (P<0.001). Despite the NH4-N, there were significant differences between the NO3-N contents of these two soils (P <=.0.05). These results showed that nitrate producing bacteria were still very sensitive to foreign compounds added to the soils. These results suggest that soil microorganisms consumed the Imazamox as C and/or N sources without being effected by different humidity conditions.