Measurement of offsets from the GPS antennae to any equipment is another important procedure during equipment setup. For example, sprayers with automatic section control require a measurement from the GPS antenna to the boom centerline. This ensures that boom sections are turned off when they (not the GPS antennae) pass over previously sprayed areas. Similar measurements are necessary for planters and spreaders to minimize skips and overlaps at the end of the passes.
Calibration of these systems is also critical for proper performance. Distribution tests should be performed for spinner spreaders to ensure that a proper pattern is being achieved, keeping in mind that different products may require their own calibration and swath settings because of density and particle sizes. For sprayers, verify that nozzles are within 5% of the manufacturer's flow rate at a given pressure. If possible, perform a flow meter calibration to confirm that actual output doesn't differ from the spray rate controller flow value. Seed drop tests can help evaluate the planter's ability to maintain proper seed populations.
When calibrating any of the systems mentioned above, it's important to remember that application errors will typically be less at the settings (speed and target rate, for example) chosen for the calibration. It's a good idea to select those calibration settings close to values that you will try to use out in the field. Performing additional checks at higher or lower settings may help you evaluate the potential for error when you deviate from your typical field operating ranges.
While technology has come a long way over the past few years, it won't solve all of our application problems; proper maintenance and management is still a must for minimizing your field errors.