How To: Calibrate A Rotary Spreader

Properly calibrated and maintained equipment will increase its performance, not only making your job easier, but more accurate as well. This is especially true when it comes to spreaders. Without proper calibration, you can do serious damage to turf. So get your tools together and follow these steps to ensure that your spreader is ready for the upcoming season.

TOOLS NEEDED FOR ROTARY SPREADER CALIBRATION

To perform calibration, you'll need your spreader, measuring tape or wheel, scale, bucket, calculator, tape or marking paint, 11 1- × 1-foot catch pans (you may use cardboard boxes cut to 6 inches high), 50 pounds of product (fertilizer), and 11 vials.

STEP ONE: DETERMINE EFFECTIVE SPREAD WIDTH

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  • Place the 11 catch pans in a straight-line, perpendicular to spread path. Catch pans should be touching side to side.

  • Start with the setting gauge approximately ⅓ open.

  • Close the hopper gate assembly.

  • Fill hopper with material.

  • Push the spreader at a normal walking speed (3 mph) over the catch pans on a paved or blacktop surface. Travel in only one direction, but make multiple passes.

  • Empty each catch pan into a separate corresponding vial.

  • Going outward from the center vial, determine which vial on each side has ½ the amount of the center vial. Count the number of vials between the two end vials and this is your effective spreading width (providing you used 1- × 1-foot square boxes and they were touching side to side).

STEP TWO: DETERMINE DISTANCE TO TRAVEL

  • Divide 1,000 square feet by the determined effective spread width. Example: 1,000 square feet ÷ 7 feet (effective spread width) = 143 feet.

  • Using a tape measure, mark off the distance to travel. Example: Mark off 143 feet. (Use flags or paint to mark start and finish.)

STEP THREE: DETERMINE AMOUNT TO APPLY

  • Read product label to determine amount of product you should apply per 1,000 square feet.

  • Weigh out 20 to 30 pounds of product. Note the exact amount added into hopper.

  • Apply the product over the given distance as determined in Step Two (143 feet).

  • Weigh product left in hopper to determine weight of product dispersed.

  • Open or close the setting gauge and repeat this process until the amount delivered is equal to the amount indicated on the label per 1,000 square feet

ACHIEVING THE CORRECT APPLICATION RATE

  • Labeled settings are approximate and should be used only as a starting point.

  • Many factors can influence product delivery rate including: operator walking speed; age and condition of spreader; weather (humidity, wind, rain, etc.).

  • Always push spreader; do not pull.

  • Push the spreader at a consistent walking speed (3 mph)

  • Always start walking before opening the operating lever and close the lever before forward motion has stopped

Source: David Woznicki and JB Toorish at LESCO Technical Services.

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© 2014 Penton Media Inc.

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