Soil and Water Relationships on the Behavior of Bensulfuron Methyl (DPX-F 5384) under the Paddy Field Condition

Abstract

Time-course changes in the concentration of bensulfuron methyl in the water of simulated rice paddies revealed a rapid decline in the concentration of the compound within 4 days of application. The decrease in water concentration was related to paddy soil type. On soils having the highest capacity to bind bensulfuron methyl, water concentrations declined more rapidly compared with soils that did not bind the compound as readily. Isothermal soil adsorption studies indicated that soil organic matter, total cation exchange capacity and soil pH influenced the degree of binding. Soils exhibiting a high content of organic matter, high clay content and low pH bound bensulfuron methyl most readily. Freundlich constants (K) were calculated for seven different soils and the values ranged from 2.1 to 112. The impact of water management was also examined in relation to the herbicidal efficacy of bensulfuron methyl.