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Calibration of Sugarcane Sprayers. Curtis Rainbolt, Ron Rice, and Les Baucum University of Florida/IFAS. Calibration. Mathematical determination of the amount of spray solution (water) applied in gallons per acre (GPA) Insures that the appropriate amount of herbicide is applied
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Calibration of Sugarcane Sprayers Curtis Rainbolt, Ron Rice, and Les Baucum University of Florida/IFAS
Calibration • Mathematical determination of the amount of spray solution (water) applied in gallons per acre (GPA) • Insures that the appropriate amount of herbicide is applied • The GPA can be changed by adjusting one or more of the following: • Pressure • Nozzle size • Ground speed • Spacing of nozzles on spray boom • Pressure has least effect on spray volume but important in maintaining proper spray pattern • Pressure affects spray droplet size and drift
Why Calibrate? • Proper calibration of sprayers will eliminate the over or under application of herbicides • Under application • Poor weed control • Need for reapplication • Yield losses due to competition • Over application • Increased chance of crop injury (narrow margin for some herbicides) • Environmental pollution (off label application rates) • Increased cost
Cost estimate for over or under application Under application resulting in re-spray* $30/acre x 100 acres $3,000 $30/acre x 1000 acres $30,000 *Does not include additional time/labor, fuel, and machinery expense Over application by 10% ($30/acre x 10% ) x 100 acres $300 ($30/acre x 10% ) x 1000 acres $3,000 ($30/acre x 10% ) x 5000 acres $150,000
Nebraska Calibration Survey • Two of every three pesticide applicators were making significant application errors • These mistakes were costing farmers from $2 to $15 per acre in added chemical expense, potential crop damage, and threatened weed competition • 75% of applicators who calibrated more than once per year were within 5% of target • How would you compare?
Prior to Calibrating • Inspect your spray equipment • Check for leaks • Look at nozzle spray patterns • Replace all faulty nozzles • Make sure screens are clean • Determine if application is banded or broadcast
Calibration Procedure • Determine calibration distance in feet from the table using band width if banding or nozzle spacing for broadcast applications • To determine the calibration distance for a nozzle spacing not in the table divide 4080 by the nozzle spacing or band width in inches
Calibration (continued) • Stake out the designated calibration distance • Do this in a field rather than a hard surface to account for tire slippage that might occur • With the sprayer in operation record number of seconds it takes to travel specified distance – repeat for accuracy and record tractor used and gear and throttle setting (RPM)
Calibration Procedure (continued) • With tractor in neutral and the throttle setting determined earlier, collect water from all nozzles for band application or from 1 nozzle for broadcast applications for the required number of seconds • The number of ounces collected equals gallons per acre on a broadcast basis. • Check delivery of all nozzles on spray boom and replace if output is off by more than 10% • Remember that total ounces may represent delivery from more than one nozzle depending on whether the herbicide is banded or broadcast.
Calibration Procedure (continued) • Ways to increase GPA • Decrease speed • Increase spray pressure • And/or use a larger spray tip
To Calculate Treated Acres when Banding • Divide band width (inches) by row width (inches) and multiply by total number of acres • Asulox broadcast rate of 4 qt/A • In a 20 acre field the row width is 60 inches and a 36 inch band will be treated. Using the formula above the number of treated acres is 12 • If Asulox is broadcasted, 4 qt will treat one acre; if banded, 4 qt will treat 1.67 acres • Remember – whether broadcasted or banded the concentration of the herbicide in the water is the same and rate per treated acre is the same
Banded Calibration Example • Asulox applied at a broadcast rate of 4 qt/A • You are spraying a 36 inch band (3 nozzles) and the row spacing is 60 inches • If you collect 20 ounces from 3 nozzles/row for time it took to travel 113 ft (36 inch band = 113 ft), then you are applying 20 gallons per acre in the banded area • A 200 gallon spray tank will treat 10 acres broadcast or 16.6 acres if the spray solution is banded. • Asulox should be added at 40 qt (10 gallons) to 190 gallons of water. • Remember the concentration of the herbicide in the water is the same whether applied on a band or broadcast.
Broadcast Example • Aatrex is being applied broadcast using a boom that has nozzles spaced 20 inches apart • In the time it took you to travel 207 ft, you caught 15 ounces of water from a single nozzle. Thus you are applying 15 GPA • You have a 300 gallon tank, so you can treat 20 acres • For a rate of 4 qts/acre you should add 80 qts atrazine to 220 gallons of water.