Drift from boom sprayers 2. Wind tunnel experiments

1. Taylor et al., 2004 Drift from boom sprayers 2. Wind tunnel experiments D NUYTTENS1, M DE SCHAMPHELEIRE2, K BAETENS3& B SONCK1 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 Objective To measure airborne and fallout spray deposits of different spray application techniques in a wind tunnel under different conditions To calculate the drift potential of different spray applications using contrasting approaches and compare these results with the reference spraying Materials and Methods • Measuring set-up • Silsoe Research Institute wind tunnel facility • 2 mm polythene collector lines → downwind spray deposits • 6 horizontal lines (H1 → H6): fallout spray deposits • 5 vertical lines (V1 → V5): airborne spray deposits • Spray liquid: Sodium fluorescein tracer (0.02%) + surfactant Agral (0.1%) Spray application techniques: • Drift potential (DP) & Drift potential reduction percentages (DPRP, %) • DP of the different spray appilcations calculated following 3 approaches: • DPV1:first moment of the airborne deposit profile • DPV2: surface under the airborne deposit curve • DPH: surface under the fallout deposit curve • DP values are compared with the equivalent results from thereference spraying → DPRPV1,DPRPV2,DPRPH • DPRP values express the % reduction of the drift potential compared with the reference • Measuring protocol • Single and static spray nozzle (10 s spraying) - 0.5 m nozzle height • Uniform wind tunnel air speed of 2 m.s-1 • Environmental conditions: RH > 90%; T= 20 °C • Hardi ISO F 110 03 reference nozzle at 3 bar to check for the repeatability • Spray deposits expressed as µL spray recovered from the lines for every liter of spray solution emitted by the nozzle • 45 experiments Results Fallout & airborne deposits Drift potential reduction percentages (%) Fallout deposits for different Hardi ISO nozzle types and sizes at 3.0 bar Fallout deposits for different Hardi ISO nozzle types and sizes at 3.0 bar DPRPV1, DPRPV2 and DPRPH values (+ 95% confidence intervals) for different Hardi ISO nozzle types at 3.0 bar Conclusions • Results show the expected fallout and airborne deposit profiles • Highest deposits closest to the nozzle and a systematic decrease with distance from the nozzle. • Highest deposits at the lowest collectors with a systematic decrease with increasing heights • For the same nozzle size (and pressure): DPRPairinclusion > DPRPlow-drift >DPRPstandard flat fan • The bigger the ISO nozzle size, the higher the DPRP values for the standard and the low-drift flat fan nozzles at a constant spray pressure • Standard flat fan nozzles: DPRPV1 > DPRPV2 > DPRPH • Low-drift flat fan nozzles: DPRPV1 < DPRPV2 < DPRPH Important in the interpretation of wind tunnel data for different nozzle types and sampling methodologies References Nuyttens D. 2007. 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 978-90-8826-039-1. available at: http://hdl.handle.net/1979/1047