PERSISTENCE OF TWO SULPHONYLUREA HERBICIDES IN WHEAT PLANTED FIELD, THRACE REGION IN TURKEY

. This study is concerning the environmental fate of chlorsulfuron and tribenuron-methyl herbicide in a wheat planted field at Thrace Region in Turkey. Use of herbicides containing these active ingredients is advised in the Marmara region in Turkey for cereal agriculture. The study was conducted in wheat planted fields where these herbicides were used. Over nine months, in each two or three week periods, soil samples were obtained from selected sampling points and herbicide residuals were determined by gas chromatography with electron capture detector (GC-ECD) and high performance liquid chromatography-mass spectrometry (HPLC-MS). As a result of these studies, persistence of chlorsulfuron was determined as approximately 1.2% at the second half of June, 2016 and tribenuron methyl seemed to be approximately 1% at the end of May, 2016. The results of the present study showed that chlorsulfuron is generally adsorbed weakly by soil when compared to tribenuron-methyl. pH, organic material, climatic factors and clay content of soil were the main factors influencing the adsorption and desorption properties of the herbicides. The results of this study demonstrated that chlorsulfuron and tribenuron-methyl residues in the soil might depend on their different chemical structures, soil temperature, precipitation and humidity