What does re-calibration of spreaders involve?

Re-calibration of spreaders primarily involves adjusting spreaders after performance checks to ensure that they are delivering the correct rate of fertilizer. This process is essential for achieving accurate application rates, which is critical for effective fertilizer use, minimizing wastage, and protecting the environment from over-application that can lead to runoff and pollution.

During re-calibration, practitioners evaluate factors such as the spread pattern, the amount of product being dispensed, and the operational settings of the spreader itself. If discrepancies are found during performance checks, adjustments can be made to the spreader's settings to optimize its performance. This could involve modifying the application rate, adjusting the width of the spread pattern, or other mechanical adjustments related to how the fertilizer is delivered.

The other options do not align with the standard procedure for re-calibrating spreaders. Increasing the speed of the motor affects the delivery rate but does not ensure accuracy without subsequent performance checks; changing the nozzle type pertains to equipment modifications rather than calibration; and emptying the spreader may be part of maintenance but does not directly contribute to calibrating for proper application rates.