Performance Comparison of Basic Pesticide Residue Prediction Models in Domestic Agricultural Environments

Objectives : This study assessed the performance of two FOCUS simulation models, Step 1 and Step 2 models which were officially used for pesticide review process in the European Union, in domestic agricultural environments.Material and methods : A performance comparison was made between two models for three selected pesticides (i.e., bifenthrin, fenitrothion and iprodione) which were widely adopted in Korean agriculture. A combination of different crop interception and runoff scenarios was used in the simulation. During the simulation, two selected crops (i.e., citrus crop and pome and stone fruits) were treated with individual pesticides at a concentration of 100 mL 5 times at 30-day intervals by foliar feeding. The simulation results of two models were also validated against field observations complied at around 500 monitoring sites over the period 2018-2023.Results : Our results found that Step 2 model had superior prediction performance in three selected pesticides than Step 1 model, and produced the simulation results which were also in good agreement with the field monitoring data. The residues of three pesticides (i.e., predicted environmental concentration, PEC) in surface water calculated from Step 2 model were generally higher for pome and stone fruits than for citrus crop. Step 2 model also predicted high pesticide residues in sediment under conditions of no crop interception and (extremely) high runoff out of various scenarios provided in the model.Conclusion : All these results demonstrated that FOCUS Step 2 model was capable of estimating PEC values at different environment media under domestic agricultural conditions.