Development and performance test of spray drift test system for sprayer with bar

The use of pesticides is an important part of modern agriculture and contributes to the productivity and the quality of the cultivated crop. Pesticide exposure via spray drift can have a negative impact on bystanders, residents, livestock, terrestrial and aquatic ecosystems. Several reviews related to drift phenomenon have been published since the negative effect of spray drift has been recognized. Spray drift is affected by environmental and meteorological conditions, the spray technique and the crop. Wind speed and wind direction are meteorological factors affecting spray deposition. Relative humidity and high air temperature can reinforce evaporation by decreasing the droplet size of particularly small spray droplets, subsequently decreasing their sedimentation velocity and making them more drift-prone. The fate of spray droplets is influenced by operating conditions such as application height, driving speed of sprayer, and nozzle spacing. Air-assisted spraying and use of shielded sprayers in general reduce spray drift. The use of an end nozzle at the edge of the field can prevent overspray of pesticides. A new equipment was developed to study spray drift of boom sprayer and to evaluate drift risk of different spray equipment in this study. ISO 22369-2-2010 had been proposed in which sprayers were classified based on the results of field tests conducted following the ISO 22866 Standard "Methods for field measurement of spray drift". However, this test required well defined and stable conditions of wind speed and wind direction with respect to the sprayer travel direction. As an alternative methodology to simplify the assessment of spray drift risk for different equipment, this study developed drift test system to assess the amount of drift generated by field boom sprayers. The system was expected to be an effective alternative for drift assessment when wind tunnel was unavailable. This study followed the ISO 22369-2-2010 standard to test the potential drift of different nozzles indoor. According to the international standard ISO 22369-2-2010, the spray drift potential of six kinds of fan nozzle (XR110-04, IDK120-03, IDK120-04, ID120-015, ID120-025, and ID120-05) were tested and evaluated indoor by measuring the drift loss and calculating the potential drift. The method could be used for direct evaluation of drift. In the test, BSF (1‰) tracers were used to test the droplet. The test showed that the droplet size and pressure were the main factors affecting drift loss (P<0.05). When the pressure was 0.3 MPa, the potential drift of XR110-04 was 33%, which was much higher than the other 5 kinds of nozzles. The potential drift loss of nozzle Lechler ID120-025 was only 6%, which was the minimum. The risk of spray drift was closely related with the spray pressure in this study. The result showed that as the spray pressure increased, the volume of the droplet diameter became smaller, which greatly increased the potential drift. The results can provide valuble information for the reduction of pesticide spray drift and drift classification.