Imidacloprid losses in surface runoff from plots cultivated with tobacco.

The loss of imidacloprid, a systemic insecticide, was determined in runoff water from loamy soil plots of various surface slopes cultivated with tobacco over a period of 174 days. Conditions were selected to simulate agricultural practices employed in the Mediterranean region. The surface slopes of plots were 0, 2.5, 5, 7.5, and 10%, and both cultivated and uncultivated (control) areas were monitored simultaneously. The cumulative losses of imidacloprid in surface runoff from tilled and untilled plots with a slope of 10% were estimated at 0.076% and 0.131% of the initial applied active ingredient, respectively, while for the plots with a slope of 0%, they were 0.003% and 0.005%. Analyses of soil samples for a 110 day period made it possible to study the kinetics of pesticide residue decrease. The average half-life was 17.8 days in bare soil and 16.9 days in tobacco-cultivated plots. [ABSTRACT FROM AUTHOR]