Calibration vital to spray success
Check nozzles and pressures for a consistent chemical spread on crops
Sprayer nozzles do wear with use over time and they are the first things to consider about sprayer calibration. What is their output at a given pressure?
A number of years ago, sprayer nozzles were standardised through the International Standards Organisation. This makes them simpler to identify and use -- red jet, red cap, blue jet, blue cap and so on.
The nozzles' capacity is also proportional to the nozzle size -- for example an 02 nozzle at three-bar pressure has an output of 0.80 litres/min, while an 04 nozzle at the same pressure has double the output at 1.6 litres/min.
The Teagasc table (right) demonstrates this but be aware: there may be a few old jets still out there.
Fan pattern nozzles, such as those in the chart above, are, for the most part, the most common type of spray nozzle used here and are what we will concentrate on in this article.
Armed with the ISO fan nozzle information and a graduated jug or similar, it is possible to check the output of each and every nozzle on your sprayer. This is certainly a worthwhile exercise because a sprayer might put out the correct amount of chemical over a given area but may not have applied it evenly across the width of the boom if there were nozzles more worn than others. This would not be known until too late and could have a serious effect on the crop's growth and yield.
Before checking nozzle outputs, it's worth ensuring that you have on appropriate personal protective equipment, gloves, overalls, etc.