Simulating the Environmental Fate of Cypermethrin Using the PeFT Rice Model

Simulation of the environmental fate of an insecticide in a paddy field is very important to come up with an effective cultural management practice that would minimize its adverse effect on the environment and the society. Furthermore, due to complexity and high cost of laboratory analysis, the use of a model is indispensable. The study is aimed at simulating the residue concentration of cypermethrin insecticide in the ponded water of a paddy field using the PeFT Rice Model. Four (4) identical paddy plots uniformly planted with the same rice variety were setup for this experiment. Each paddy plot was uniformly sprayed at the same rate with cypermethrin insecticide. Water samples were collected from each plot during Days 0 (before pesticide application), 1, 2, 3, 5, 7 and 14 following standard protocols and were analyzed using the liquid chromatography method at a third party laboratory. Result of the study revealed that cypermethrin insecticide could last in the paddy water up to five (5) days after its application. Hence, in order to prevent or minimize insecticide contamination of proximate bodies of water that serves as drainage basins, lowland rice farmers should ensure containment of paddy water and should not be drained from the field up to five days after the application of the insecticide. Moreover, the PeFT Rice Model can correctly simulate the environmental fate of cypermethrin insecticide in the paddy field as proven by its very low root mean square error (RMSE) value of 5.78%.

Keywords –Environmental fate of pesticide, PeFT Rice Model, pesticide concentration simulation