Application of a one-dimensional model of flow in unsaturated soils and transport of herbicides in agricultural areas

Abstract

In order to minimize adverse impacts beyond the place of application, it is necessary to predict the behavior of pesticides released into the environment. This means that we must understand what happens to a pesticide that has been applied in the field and that we must be able to predict its destination in the environment. For this purpose, we studied an experimental agricultural plot at the National Institute of Agricultural Technology (INTA) in the town of Manfredi (Córdoba, Argentina). The contents of water in the soil were measured (by neutron probe and by the gravimetric method) along with precipitation at the site during a certain period in order to model the process of humidification. Pollutants’ contents were also measured at various depths and at different times of atrazine application. This data was then used to model the process using the software HYDRUS. The results show that the model underestimates the moisture content present in the upper horizon, while in deeper layers, under normal events of rainfall and irrigation, the humidification front does not generate a direct recharge from the phreatic water. The study established that numerical simulation is a valid tool for studying the movement of flow and the transport of contaminants in the unsaturated zone. The lack of field data is main limitation to assessing the validity of the model.