Step 6 of 6 - calibrating your knapsack sprayer for pesticide dose and spray mix/water volume

Now complete the calibration by checking that the right amount of spray is being emitted over a known area in the right spray pattern.

Place the sprayer down on a flat piece of ground and mark the water level in the sprayer.

Next spray the marked out area at the pressure, nozzle height and spraying speed practiced.

Then place the sprayer on the same piece of flat ground and mark the new water level.

Use a measuring cylinder and carefully add water to raise the level back up to the original mark.

How much should we have sprayed over 25 square meters? First calculate how much we should spray over 1 square meter:

One hectare is 10,000 square meters. To spray 200 liters evenly over 10,000 square meters, we should spray 200/10,000 which is 0.02 liters per square meter. To spray 25 square meters we should have used 25 x 0.02 liters which is 0.5 liters or 500 ml.

In this demonstration we have used only 450 ml so we have sprayed too quickly

et nous devons recommencer en pulvérisant un peu plus lentement. Nous sommes maintenant au point.

500 ml has been sprayed out and so this is the speed at which we will spray.

This sprayer is now properly calibrated and these nozzles when used as we have in this calibration, will spray the water volume rate needed and as advised on the label (for this spraying task).