The presence of ametryn has been detected in surface water in agricultural areas, including paddy fields. In this study, the process of ametryn adsorption and desorption were investigated in two types of soil, paddy field and irrigation canal soil. The soil samples were obtained from a paddy plantation in Padang Tembusu, Seberang Perai Utara, Pulau Pinang, Malaysia. Ametryn solutions were dosed according to recommended farmer usage and their concentrations were analysed in different concentrations ranging from 1 mg/L to 30 mg/L. The filtered supernatant was extracted using SPE, a solid-phase extraction method, while the ametryn concentrations were determined by GC-FID. The results were characterized using Freundlich and Langmuir isotherm for both studies, which indicated the occurrence of monolayer and multilayer adsorption. The recovery rates of ametryn from paddy field and irrigation canal soils were 87 and 91 respectively. The equilibrium time for ametryn sorption in the soils reached approximately 6 hours. The results show that the percentage adsorption of ametryn is higher in paddy fields than in irrigation canal soils. Meanwhile, the percentage ametryn desorbed into the aqueous phase was higher in irrigation canal soils than paddy field soils as showed that ametryn molecules were bound weakly to clay and sandy clay soils. Based on the studies on adsorption of ametryn, paddy field soil demonstrated high R2 values of 0.8731 and 0.8161 were recorded compared to irrigation canal soil based on Freundlich isotherms. Langmuir isotherms demonstrated that the R2 values for paddy soil sample and irrigation canal soil amounted to 0.6266 and 0.2141. In the examination of desorption, both soil samples achieved the same R2 values, which had balance and better fit using Freundlich isotherm. However, the desorption study for irrigation soil using Langmuir isotherm was unable to satisfy both soil samples. It could be concluded that ametryn in paddy soil with 43.81 residual may threaten the water streams, compared to irrigation canal soil with 19.66 of ametryn residual. Significant correlations were found among sorption of ametryn, organic matter and clay. It was also indicated that ametryn could be returned to the water bodies via the desorption process, which increased the risk of ametryn contamination at nearby water bodies. © 2023 AIP Publishing LLC.