A drift prediction model for the Tunisia context: A validation approach. Bahrouni, H., Ben Nouna, B., Sinfort, C., Hamza, E., Chaabane, H. and Ben Abdallah, M.A. (Tunisia / France)

Abstract

To improve agricultural production, pest control is necessary. To achieve this objective, pesticide application is one of the most practiced methods. But, for a better coverage of the target, this technique requires small droplets to control pests efficiently. However, during crop spraying, important quantities of this droplet category are transferred to the environment, with negative impacts on air, soil, water and health. So, the different compartments ofthe environment will be polluted, especially in an intensive irrigated system.The need of prediction of spray drift has led to the development of a global approach that evaluates drift potential and plant retention in Tunisian context. The central component in this approach is a drift prediction model “DriftL”. It was developed using an advection-diffusion representation for diameter classes representing the spray and it includes evaporation simulation.Tests were set up in laboratory conditions with different nozzle settings in a wind tunnel to develop the model and under a mobile boom to evaluate plant retention. Both wind tunnel and mobile boom tests were used in a combined approach to evaluate the amount of droplets lost in the air (volatilization). Predictions of these approaches were finally compared to field test results with two spraying setups (spraying Volume Median Diameter of 127 and 322 µm). DriftL was compared to threeothers Drift models: DRIFTSIM, AgDrift and the model of the European group Forum for Coordination of Pesticide Fate Models and their Use (FOCUS). The Federal Biological Research Center for Agriculture and Forestry in Germany (BBA) drift tables are referenced in the literature and are widely used by the scientific community, so they were used as reference values for comparing the four model results. These comparisons showed that the combined laboratory and modeling approach give coherent results that could be used with few improvements to achieve a global balance of pesticide losses and provide farmers with a tool to decrease them.

Keywords

• Air
• drift
• drift model
• ground
• pesticide losses
• spraying