Drill Type Spreader Calibration

Calibration of drill type spreader includes shop and field runs. In both stages, the fertilizer emitted from a single applicator is collected and weighed. To ensure uniform distribution through all single applicators, adjustments must be made to balance the output in all individual applicators for all rows.

Step 1: In the shop, lift the planter drive wheel with a jack to allow it to be turned by hand for a specific number of revolutions (value C in the following worksheet).  It is recommended to rotate the drive wheel at least 30 revolutions.

Step 2: Measure the planter row spacing distance (value E in the worksheet) and the planter drive wheel perimeter.

Step 3: In soft soil a drive wheel slippage of up to 10% is expected, therefore field calibration is necessary in order to confirm and fine tune the shop method calibration. In the field, measure the total distance travelled by the planter drive wheel equivalent to the same number of revolutions used in the shop calibration. Divide this field distance by the number of revolutions to get the “actual” drive wheel perimeter(value D in the worksheet).

Step 4: Insert these values into the appropriate calculation in Worksheet 1, in order to measure the actual application rate. If the actual application rate is different from the desired rate, the spreader must be adjusted.

The parameter which is easiest to change is the fertilizer flow (the amount of fertilizer collected from the spreader in 60 seconds), which is directly proportional to the change for the preferred application rate. For example, if the measured application rate is too low, the spreader must be adjusted to increase fertilizer flow. The desired fertilizer weight (value B in the Worksheets) can then be inserted in the Worksheets and calculated. The spreader should be adjusted to reach this value.

Next: Worksheet 1: Drill Spreader Calibration Calculation

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