Bentazon is a post-emergence contact diazinone herbicide used to control annual weeds in a variety of crops especially in rice . Bentazon soil–water distribution coefficient (Kd) is 0.72 that indicate it does not bind to, or adsorb, to soil particles and it is highly soluble in water. These characteristics usually suggest a strong mobility and potential for groundwater contamination. Bentazon, however, is so rapidly degraded in upper soil layers by sunlight and soil microbes that it does not tend to move (leach) below the surface layer of the soil. Its rapid degradation is expected to
prevent the contamination of groundwater. Bentazon is moderately toxic by ingestion and slightly toxic by dermal absorption