6.3.3 A simple calibration procedure

There are various methods and devices to aid calibrating manual sprayers; a simple method appropriate for smallholder tree crops is as follows:
 

1. Place a small volume of clean water into the sprayer tank and operate pump to check for leaks and that the nozzle is operating correctly.
2. Empty the sprayer then put in a known volume - say 5 litres into a 15-litre tank.
3. Spray part of the crop and measure the number of trees treated.
4. This number multiplied by 3 will give the number of trees treated by one tank-load.
5. From this, the number of tank-loads needed to cover the whole of the crop area can be estimated. If 12 tank- loads are needed for one hectare, then the dosage of pesticide per hectare divided by 12 equals the amount that has to be added to each tank-load.