Calibrating a sprayer is critical to making an accurate and safe application of a crop protection product. Typically, calibration is defined as checking the sprayer output to make sure it is spraying the proper amount of material as stipulated by the label for the product you are applying.
With today’s modern boom sprayer, electronic rate controllers are used to maintain a uniform application volume (GPA) across the sprayed field. However, even if the rate controller is accurately measuring the amount of output is not necessarily guaranteeing that each nozzle is exactly at the same output. In other words, if one or more nozzles were clogged emitting no spray, it is likely that the rate controller will still be reporting an accurate application volume. With clogged nozzles there would not be a uniform application and skips in spray would result in crop protection breakdown. In fact, the nozzle next to the clogged nozzle is likely to be over applying to compensate because of the demand from the rate controller to maintain a uniform application volume. Thus, one aspect of calibration is making sure that every nozzle on the spray boom is spraying as near as possible the same amount of material. This can only be done with a collection so that the output of every nozzle on the boom is known. A typical collection would involve using a catch container and a stop watch to measure each nozzles flow and compare.
A new tool for calibration is the SpotOn® digital sprayer calibrator. This tool is accurate for most boom sprayer setups and ideal for longer booms with more nozzles. More information on this device can be found at www.innoquestinc.com.