Primary Column Study on the Leaching Behaviors of Herbicide Mesotrione in a Paddy Soil and a Silty Clay Loam Soil

Leaching behaviors of herbicide mesotrione in soil columns with different physic-chemical situation were studied using physical simulating artificial rainfall method. Soil columns used in this study were 10cm in the internal diameter with the height of 25cm, the amount of mesotrione added was 15mg, and the rainfall volume was set to 60mL/h. Results showed that the concentration of emotion was increased with the deepness, and the mostly distribution were found to be in 15 similar to 21cm layers in soil columns after 10 hour's continuous leaching. At the same time, about 4% of added mesotrione was leaching through columns with silty clay loam soils. Leaching properties of mesotrione was found to be primarily related to soil pH, but less extent to extent to soil organic carbon content (%OC). As soil pH increased, the adsorption capacity K-d values (ranged from 3.11 to 3.709L/kg) decreased as mesotrione dissociated from the molecular to anionic form. It wad conclude that mesotrione was easy to be leached into lower surface soil and brought some risks to groundwater, especially in soils with higher pH values, such as silty clay loam soils.