Document Sample

```					Spreader Calibration

Getting the most out of your
fertilizer applications
• Are we paying attention to what is being used
from an equipment perspective?
• Is calibration important enough to dedicate the
time to discuss and do?
• When was the last time we calibrated our
• The product might get blamed but, fertilizer
performance may not be the issue…many of the
perceived failures in the field are due to operator
error, substandard equipment or equipment that
just hasn’t been calibrated…

2 steps required for calibration
1. Determine the “effective swath width” of
spreader…note this is not the same as
–   Granular product throws distance to either side of
–   Distribution is not uniform
–   Even distribution achieved by overlapping
2. Measure amount of product being applied
–   “collection trays”
–   “catch pan” method
–   “weigh in-weigh out” method

• Calculate the area covered by the
distance
Determine the throw distance and the
“effective swath width”
– Throw distance = 20 ft
– Example “effective swath width” = 12 ft
• Measure and mark a distance to travel
– 83’4” x 12 ft = 1,000 ft2

• Measure amount of product being applied
– “collection tray” method
• Use the center collection tray from the previous effective
swath width determination
– “catch pan” method
• Attach a collection bag or container around the impeller to
catch the product being applied
– “weigh in-weigh out” method
• Weigh total product at start. “Apply” the product to a benign
surface then re-weigh remainder of product
• Repeat the procedure 2-3 more times or until
consistent results are obtained (10%)

• Set the hopper opening to a low to medium range setting
• Fill the hopper half full with a product
• Push the spreader at a comfortable walking speed…the
same pace used to actually apply product…open the
hopper…travel the marked off distance…close the
hopper (the same concept applies to fairway and rough
• Beware…a 6’4” assistant will not walk as quickly as a
5’5” superintendent and tractor speed needs to be
consistent for large areas…
Example calibration

• Target is to apply 0.5 lb / 1000 ft2 nitrogen
using ammonium sulfate (21-0-0)
– Ammonium sulfate has 21% N
– 0.5 lb N / 21 % = 2.38 lb ammonium sulfate
• Spreader must be calibrated to throw
2.38 lb ammonium sulfate / 1000 ft2

• Travel Speed (walking or riding) is often
underestimated…
• +/- 0.5 mph = +/-16.7% change in rate or
.167 lbs on a 1 lb application!!!
• +/- 1.0 mph = +/-33.3% change in rate or
.333 lbs on a 1 lb application!!!
• Tire Pressure at 20lbs critical…
• Regular lubrication of the gear box and shut off
valves…Do it regularly!
• Be aware that “effective swath width” and “actual
spread width” are NOT one and the same…
on ‘starts and stops’
Turns with
Rate x Two Directions
Rate x One Direction
Rate x Half Width

Recommended!!!
Reminders…
• Settings are “suggested” only and annual
calibration is important as equipment wears or
changes and personnel change.
• We calibrate our sprayers on a regular interval;
• You spend wisely on fertilizer…why not make
sure it gets where you want it to go as accurately
as possible!
• Questions? Contact me at