Development of drift reduction technology for field boom sprayers

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This research was conducted to investigate spray operations, to analyze the spray drift mechanism by wind tunnel experiments, and to develop the spray drift reduction technology for field boom sprayers.1. From May to August every year, farmers in Tokachi are busy doing pest control operations. They usually do the operation in the early morning and evening when the wind velocity is low. Large-scale farmers are more advanced in the use of high-efficiency sprayers, the trailer and self-propelled types , with application width of 20 m or more. The wind is one of the factors that disturb the timing of the application of chemicals to control pests and diseases. Therefore, farmers desire to use drift spray reduction technology that can still be operated even in mild to strong wind conditions.2. The logarithm of the drift distance linearly increases, as the spray particles become smaller. It also increases, as the discharge velocity of the spray particles becomes slower. For conventional nozzles, the drift increases exponentially beginning at the application height of 40 cm and wind velocity of 1 m/s. However, when driftless nozzles were used, the drift was reduced. to less than half to that of the conventional nozzles. At no wind condition, the spray distribution pattern extends to the direction of the nozzle. When there is a wind, the drift in the leeward side increases, in sprayers with long boom, the use of automatic control device is necessary to keep the application height constant.3. The use of the boom height controller and the selected driftless nozzle decreased the spray drift of the conventional sprayers by almost 70%. This technology made it possible to spray at wind velocity condition of up to 2.8 m/s. Therefore, the technology is extremely effective in reducing the drift in spraying operations.