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Pesticide Applications

Pesticide Applications. Equipment and Calibration. Department of Agricultural and Biological Engineering. Spring 2017. The Basics. Pesticide Application Goals Control Pest – thorough and uniform coverage Reduce drift and other types of misapplication. Sprayer Components.

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Pesticide Applications

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  1. Pesticide Applications Equipment and Calibration Department of Agricultural and Biological Engineering Spring 2017

  2. The Basics • Pesticide Application Goals • Control Pest – thorough and uniform coverage • Reduce drift and other types of misapplication

  3. Sprayer Components • Tank – holds spray • Stainless steel – Strong but expensive • Polyethylene– Inexpensive but breaks down with UV Exposure • Agitation needed to prevent settling out (DF, WP, …) • Pump – Moves spray and provides pressure for atomization • Boom – holds nozzles, affects overlap and drift • Check valve – prevent drips • Nozzles – orifice size affects amount of spray applied

  4. Pump Selection

  5. Pump Selection

  6. Determining required pump output • Determine boom flow rate requirement • Depends on Application Rate, Travel Speed and Boom Width • Add agitation flow rate requirement • Depends on pesticide formulation • Add an excess flow factor of 20% • Ensures operation within limits

  7. Determining Required Pump Output Agitation Flow Rate… Boom Flow Rate… GPM→ Flow rate (gallons per minute) GPA → Application rate (gallons per acre) MPH → Ground speed (miles per hour) BW → Boom width (feet) 495 → Constant used for converting units K → Agitation Factor K = 0.05 for liquids K = 0.125 for wettable powders and flowables

  8. Droplet Size • Droplet size influences coverage and spray drift • Small droplets provide better coverage but are more likely to drift • Nozzles produce a range of droplet sizes – Droplet size spectrum

  9. Droplet Size • Droplets measured by diameter in microns (µm) • Spray droplets smaller than 100 micronsare at risk of drifting

  10. Droplet Size Spectrum • VMD – Volume Median Diameter • Representative droplet size where half the spray volume is in smaller droplets and half is in larger droplets • %<100 microns • Percentage of spray volume in droplets smaller than 100 microns (think drift potential) • Droplet Spectrum Categories

  11. Droplet Spectrum Categories AG

  12. Droplet size and number = = 1 500µm droplet 8 250µm droplets 64 125µm droplets

  13. Droplet Deposition • Small droplets deposit more efficiently than larger droplets • Large droplets can rebound or shatter into smaller droplets • Target influences deposition • Plant Part – Leaf, stem, etc. • Orientation and interception angle • Wettability – cuticle surface

  14. Choose Nozzles that provide good coverage and minimize drift

  15. Common Nozzle Types

  16. Common Nozzle Types

  17. Particle Drift is Influenced By…

  18. Strategies to Reduce Drift Coarser Droplets Finer Droplets Finer Droplets Coarser Droplets Finer Droplets Coarser Droplets Control Droplet Size

  19. Nozzle Type and Orifice Size Impact Droplet Size

  20. Nozzle Type and Orifice Size Impact Risk of Drift

  21. Weather and Drift

  22. Nozzle Overlap • Determined By: • Nozzle Fan Angle • Nozzle Spacing • Boom Height

  23. Calculating Overlap Nozzle Spacing We can find our percent overlap from the Sprayed Width and Nozzle Spacing NS SW

  24. Sprayer Calibration Formulae Need Application Rate… Need Nozzle Flow Rate… GPA→ Spray application rate in gallons per acre GPM → Nozzle flow rate in gallons per minute MPH → Ground speed in miles per hour NS → Nozzle Spacing in inches 5,940 → Constant used for converting units

  25. Calibration Example You are applying a fungicide to soybeans. Your spray application rate will be 10 GPA, you will be spraying at 6 MPH and you have 20 inch nozzle spacing on your sprayer. What is the required flow rate for this application? We Know… • GPA = 10 • MPH = 6 • NS = 20 Find…  • GPM?

  26. Calibration Example • We can now choose a nozzle • Required GPM = 0.20 • Let’s assume we need a Medium droplet spectrum We choose a TT11002 @ 40 PSI

  27. Rate Controllers and Droplet Size • Monitor application factors • Flow Rate • Pressure • Speed • Information entered by applicator • Effective Sprayed Width • Target GPA

  28. Rate Controllers and Droplet Size • Controller maintains GPA during speed changes • Adjusts nozzle flow rate using PRESSURE • Changes Droplet Spectrum

  29. Speed Change With Rate Controller • We setup our sprayer as follows • Nozzle Spacing 20 inches • GPA = 10 • Nozzle TT11004

  30. Speed Change With Rate Controller • Without changing our sprayer setup, we increase speed to 18 MPH. • Rate controller must increase pressure to maintain GPA • Exceeding nozzle pressure limit; unknown droplet size

  31. Pulse Width Modulation • Computer controlled solenoid valve on each nozzle controls flow of spray • Flow stopped/started 10 times per second • Duty Cycle: period of time nozzle is held open during each pulse cycle • Alter duty cycle to adjust nozzle flow rate • Independent control of flow rate and pressure

  32. Aerial Applications Equipment and Calibration

  33. Agricultural aircraft • Fixed and Rotary Wing • Speed: 50-170 MPH • Guidance – GPS with GIS

  34. Agricultural aircraft • Centrifugal Wind-driven pumps • Wet Booms • Tank capacity up to 800 gallons

  35. Controlling Droplet Size • Nozzle type and orifice size • Boom Pressure • Nozzle deflection angle and orientation • Angle at which spray enters high speed air flow • Increased shear = smaller droplets • Decreased shear = larger droplets Large droplets Medium droplets Fine droplets

  36. Boom Positioning • Need to Keep nozzles out of turbulence • Trailing edge of wing • Wing tip vortices • Propeller wash

  37. Boom Positioning • Reduce length of boom • keep spray out of wing tip vortices

  38. Boom Positioning • Reposition nozzles behind propeller • Nozzle drops under fuselage

  39. Boom Positioning • Lower booms away from wing

  40. Questions? Matt Gill – gill14@Illinois.edu

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