Distribution and Mobility of Herbicide $^{14}C$-Molinate in a Rice-Paddy-Soil Lysimeter

This study was designed to assess molinate fate in the lysimeter by measuring the total radioactivity in the leachate, evolved , and -residues in soil and rice plant. The amounts of applied in the leachate from the lysimeter for 20 weeks were 1.05% in 2.31 pore volume (217,465 mL) at the first and 0.34% in the second year, respectively. The amount of evolved from the lysimeter accounted for 6.47% and 0.03% of applied in the first and second year. The -activities in the soil layer of the lysimeter were distributed 18.0% (1st) and 13.3%(2nd) in the depth of 0 to 10 cm, 4.3 (1st) and 1.1% (2nd) in the depth of 10 to 20 cm. Most of the applied was detected in the top 20 cm soil layer. Total in rice plants grown at lysimeter were detected 11.46% of applied . 11.11% in straw, 0.24% in brown rice grain, 0.08% in chaff and 0.03% in ears were distributed in the first year. Consequently, environmental fate of molinate using lysimeter simulating a paddy rice field were investigated 25.24% in soil, 11.64% in rice plant, 1.05% in leachate, 6.74% in evolved and 0.02% in volatilized organic chemicals in the first year.