Contact: Drift from boom sprayers 3. Field drift experiments To investigate the effect of meteorological conditions and spray application technique on the amount of near-field sedimenting spray drift D NUYTTENS 1, M DE SCHAMPHELEIRE 2, K BAETENS 3, D DEKEYSER 1 & B SONCK 1 1 Institute for Agricultural and Fisheries Research (ILVO), Technology & Food, Agricultural Engineering, Belgium 2 Department of Crop Protection, University Ghent, Belgium 3 MeBioS, Department Biosystems, Catholic University of Leuven, Belgium Measuring set-up  Experiments performed on grassland  24 Machery – Nachel filter paper collectors (type 751, 0.25 m x 0.25 m)  Spray liquid: brilliant sulfoflavine (3 g.L -1 ) + surfactant Tween 20 (0.1%)  Meteorological measurements Wind speed & direction at 1.50 m & 3.25 m (ultrasonic) Turbulence intensity, dewpoint temperature, atmospheric stability, solar radiation Temperature and relative humidity at 1.25 m & 2.15 m Objective Materials and Methods Results Nuyttens D, De Schampheleire M, Baetens K, Sonck B The influence of operator controlled variables on spray drift from field crop sprayers. Transactions of the ASABE. 50(4): ISSN: Nuyttens D Drift from field crop sprayers: The influence of spray application technology determined using indirect and direct drift assessment means. PhD thesis nr. 772, Katholieke Universiteit Leuven. 293 pp. ISBN available at: Effect of meteorological conditions for the reference spraying  32 drift trials with the reference spraying at a wide range of meteorological conditions Spray application techniques: DRP values (± sd) for different Hardi nozzle types at 3.0 bar compared to the reference Important effect of weather conditions (T, V 3.25m and X H 2 O ) on the amount sedimenting spray drift → Drift prediction equation Drift prediction equation can be used:  to quantify the effect of meteorological conditions on the amount of spray drift  to compare measurements using different techniques to the reference spraying → DRP  to perform spray drift risk assessments Nozzle type, size and spray pressure have an important effect on the amount of spray drift Drift prediction equation + DRP of a certain spray application technique References Conclusions Measuring set-up & protocol  61 field drift measurements according to ISO  Hardi Commander Twin Force trailed field sprayer Nozzle spacing and boom height of 0.50 m Driving speed of 8 km.h -1 Without air support, 27 m spray boom TemperatureWind speedAbsolute humidityDrift distance Validated non-linear statistical drift prediction equation (R² = 0.84): Drift percentage Predicted drift curves for the reference spraying to illustrate the effect of a. absolute humidity (X H 2 O ), b. temperature (T) and c. wind speed (V 3.25m ) a.b. c. Drift Reduction Potential (DRP, %)  DRP expresses the total amount of drift reduction of a specific spraying compared with the reference spraying  Calculated by comparing the measured drift curve of a specific spraying with the predicted drift curve of the reference spraying at the same weather conditions Expected drift curves for any weather conditions Predicted drift curves for different Hardi nozzle types at 3.0 bar when T = 16°C, V 3.25m = 3 m.s -1 and X H 2 O = 8 g.kg -1 realistic sedimenting field drift data for varying weather conditions Drift curves for F , F and Injet 03 nozzles at 3.0 bar when T = 16°C, V 3.25m = 3 m.s -1 & X H 2 O = 8 g.kg -1 together with drift data from different other studies