Variable rate dosing in precision viticulture : use of electronic 1 devices to improve application efficiency

2 Dept. Agro Forestry Engineering– Universitat de Lleida 5 6 Abstract 7 Two different spray application methods were compared in three vine varieties at 8 different crop stages. A conventional spray application with a constant volume rate per 9 unit ground area (l·ha -1 ) was compared with a variable rate application method designed 10 to compensate electronically for measured variations in canopy dimensions. An air-blast 11 sprayer with individual multi-nozzle spouts was fitted with three ultrasonic sensors and 12 three electro-valves on one side, in order to modify the emitted flow rate of the nozzles 13 according to the variability of canopy dimensions in real time. The purpose of this 14 prototype was to precisely apply the required amount of spray liquid and avoid over 15 dosing. On average, a 58% saving in application volume was achieved with the variable 16 rate method, obtaining similar or even better leaf deposits. 17 18