Evaluation of the PESTFADE model using field-measured data from a sprinkler-irrigated soybean field in Pathumthani, Thailand

This study focused on the testing of a process-based, numerical model known as PESTFADE (PESTicide Fate And Dynamics in the Environment), in a sprinkler-irrigated soybean plot located at the Asian Institute of Technology experimental farm. Field soil water content (SWC) and metribuzin residue adsorbed at soil profile depths of 0–10, 10–20 and 30–40 cm over different time periods were intensively measured by the gravimetric method and by Liquid Chromatography Tandem Mass Spectrometry, respectively. The model performed relatively well for simulating SWC at 10–20 cm and metribuzin residue concentration at 0–10 and 10–20 cm soil profile depths with R2 values as high as 0.99 and relative error values as low as−0.22; the model performed relatively poorly at 30–40 cm soil profile depth. The results indicate that when properly calibrated, PESTFADE can be used to predict the movement of water and metribuzin through the soil profile for tropical zones.