2012 Volume 37 Issue 1 Pages 20-27
A micro paddy lysimeter (MPL) was employed to monitor the behavior of nursery-box-applied imidacloprid granules in the rice paddy environment using two treatment methods, i.e. before transplanting (BT) and at sowing (AS). Tested application rates were three-fold the recommended rate. Under a water management scenario in an actual field, the behavior of nursery-box-applied imidacloprid granules in paddy water and paddy soil in MPL was comparable with field monitoring data in the literature. Imidacloprid concentration in water peaked at 189±36 μg/L and 13.1±1.4 μg/L at 1 day after transplanting (DAT), and the half-lives (DT50) were 2.5 days, and 4.7 days for BT and AS treatments, respectively. In the soil profile, the maximum concentration of imidacloprid at 21 DAT was 65.6±0.4 μg/kg and 39.7±4.9 μg/kg in the 0–2.5 cm layer in the inter-row zone for BT and AS treatments, respectively. Imidacloprid was found in the 12.5–15.0 cm layer at 3.2±0.7 μg/kg for BT treatment and 13.7±3.8 μg/kg for AS treatment, in the inter-row zone. In AS treatment, imidacloprid mainly stayed in the root zone (0–5 cm surface soil layer), and its concentration was 895±4 μg/kg at 21 DAT. MPL presented as a convenient and alternative tool to monitor the behavior of nursery-box-applied pesticide in the rice paddy environment.
