Modeling and simulation of trifluralin herbicide movement due to its application on soils by chemigation

The Trifluralin (TFN) is a pre-emergent herbicide which is widely used in agriculture. Usually, this pesticide is directly applied to the soil, where it can remain for long periods or can be transported. In this sense, knowing the dynamics of an herbicide soil transport is essential to avoid environmental contamination problems and risks to human health. Thus, this study aims to model and simulate TFN movement on soils with two different textures, a sandy loam and clay loam soil. It was considered that the herbicide was applied via chemigation trough a subsurface drip irrigation system, under a non-steady regime. Therefore, the transport parameters of TFN in these soils and physical-hydric characteristics of these were used, while the physical environment modeling were conducted using the Hydrus 2D software. The results showed that both in sandy and clayey soils, the TFN tends to be retained by the soil, close to where it was applied, not exceeding a layer greater than 2.5 mm outside the dripper radius, even in more favorable conditions such as the presence of irrigation. Finally, it could be concluded that this herbicide movement in the soil is of low potential, due to this product high solid-liquid partition coefficient (Kd), even in sandy soil, which has low cation exchange capacity (CEC).