Application Technology: Sprayer Calibration

Table of Contents

1. Field Boom-Type Sprayer Calibration
• Instructions
• Sample Calculations
• Band Spraying
2. Hand-Held/Backpack Sprayer Calibration
3. Other topics in Application Technology
   • Introduction
   • Care and Use of Equipment
   • Determining Amount of Herbicides Needed
   • Materials, Mixing and Mixtures
4. Related Links

Field Boom-Type Sprayer Calibration

(Determining application rates in L/ha.)

There are many ways of determining the number of litres of spray material that are being applied to 1 ha of land.

Instructions

1. Measure the time.
   • Place 2 stakes 50 m apart in the field.
   • Select the gear and throttle setting (rpm) at which you plan to spray. Half-fill the sprayer with water.
   • Drive the distance between the stakes three times, timing each pass. Each time, make sure the tractor is at the desired speed as you pass the first stake. Keep driving at this speed until you pass the second stake.
   • Note the average time of the 3 passes.
2. Measure the average nozzle output.
   • Park the sprayer with the PTO engaged and the throttle adjusted to reach the PTO speed set in the test run.
   • Adjust the pressure regulator to the desired working pressure with full flow to the boom.
   • Collect the output from each nozzle for the average length of time needed to travel the 50 m in the test run.
   • Enter the nozzle outputs into the equation below.
   • If any nozzle is more than 5% above or below the average output, it should be cleaned or replaced.
3. Measure the nozzle spacing in metres.
4. Use the following formula to determine the sprayer output:
   Sprayer Output (L/hectare) = (Average Nozzle Output (mL) x 0.2) ÷ Nozzle spacing (metres)
5. Calculate the actual area sprayed after each tank of spray solution is applied. Recheck the sprayer calibration after each tank of spray is applied by dividing the volume sprayed by the area sprayed. The nature of some products may slightly alter the calibration from that of clean water.
6. Growers who prefer to measure in litres/acre or gallons/acre can use the following conversion guide.
   • Litres/hectare X 0.4 = L/acre
   • Litres/hectare X 0.09 = Imp. gal/acre
   • Litres/hectare X 0.11 = U.S. gal/acre

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Sample Calculation

Average time to travel 50 m (164 ft) = 24.5 sec

Average amount of liquid collected per nozzle for 24.5 sec = 525 mL
Nozzle spacing on the boom = 0.5 m (approx. 20 in.)

Application rate = (525 mL ÷ 0.5 m) X 0.2 = 210 L/ha

210 L/ha X 0.4 = 84 L/acre

210 L/ha X 0.09 = 18.9 Imp. gal/acre

210 L/ha X 0.11 = 23 U.S. gal/acre

Band Spraying

If the sprayer has 10 nozzles and each nozzle covers a 36 cm (0.36 m) band, the total width of the spray patterns (swath width) is: 10 x 0.36 or 3.6 m.

Note 1: Sprayer calibration bottles or kits are available from a number of suppliers. For further information contact your local office of the Ontario Ministry of Agriculture, Food and Rural Affairs or manufacturers of sprayers, sprayer parts or herbicides.

Note 2: For banded spray applications, measure the width of the spray band (at the soil surface or surface of the crop canopy) and enter this value into the formula instead of the "nozzle spacing". Note that in band spraying the acreage sprayed is not the same as the crop acreage. (When broadcast spraying a row crop with 1 m rows, the whole field is treated. A band spray may only treat 30 cm over each row. Therefore, only 1/3 of the field is actually treated.) The herbicide rates referred to in most herbicide publications and labels refer to the actual area sprayed unless otherwise stated.

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Hand-Held/Backpack Sprayer Calibration

Many people use small hand-held or backpack sprayers for treating problem areas or spraying areas that were missed. Calibration of these sprayers is as important as calibrating your field sprayer.

Method I

1. Measure an area that is 100 sq. m.
   e.g., 10 m x 10 m, or 25 m x 4 m.
2. Fill the spray tank with water. Mark the level on a measuring stick. Pump to the pressure that will be used during the pesticide application.
3. Spray the water over the 100 sq. m area. Walk at a steady pace, taking care to apply it as evenly as possible, just as you would when applying pesticide.
4. Measure the amount of water needed to refill the spray tank to the mark on the measuring stick. This amount will be the sprayer output per 100 sq. m.

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Method II

1. Set 2 stakes 50 m (164 ft) apart in the field.
2. Half-fill the sprayer with water
3. Walk the 50 m three times at a steady pace. Calculate your average time to travel the 50 m.
4. Measure the width of the band sprayed by the nozzle (in metres) at your walking pace.
5. Pump the sprayer for the same amount of time as calculated in step #3, collecting the liquid from the nozzle in a measuring device.
6. Application rate (L/ha) = (mL liquid per nozzle x 0.2) ÷ Band width (metres)

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Method III

1. Partially fill sprayer. Pump to the pressure you will use during the pesticide application.
2. Spray to determine width of swath (in metres).
3. Walk at a steady pace for 15 sec. Measure the distance (in metres).
4. Multiply spray width times distance traveled to provide the area (in square metres) sprayed in 15 sec.
5. Spray into a measuring device for 15 sec. (Gives amount of solution sprayed in 15 sec.)
6. Application rate (L/ha) = (amount sprayed ÷ area (length x width)) - ((L x 10,000) ÷ sq. metres)

To convert the application rate of any pesticide to the amount required for a small area, follow this guide:

• 1 kg/ha = 10 grams/100 m²
• for liquid measure, 100 L/ha = 1 L/100 m²

Source: Ontario Pesticide Education Program Manual 1995.

Related Links

• Weeds in Ontario
• OMAFRA Sprayer Calibration Calculator
• Problem Weed Control in Field Crops
• Integrated Pest Management (IPM)
• Pesticide Application and Safety
• Pesticide Companies and Agents
• OMAFRA Sprayer Calibration Calculator
• Search the PMRA website
• OMAFRA Publication 505: Ontario Weeds
• OMAFRA Publication 75: Guide To Weed Control