Put on the appropriate personal protective equipment.
Clean the filter, nozzles and tank, and check the pressure gauge and pump. Make sure there are no leaking hoses or fittings.
Measure the swath width.This is the boom width plus the distance between the two nozzles in metres.
Fill tank with clean water and prime spray unit to operating pressure.
Measure the amount of liquid put out by each nozzle over one minute. Change any faulty nozzles and record the total output in litres of all the nozzles combined.
Record the time in seconds it takes to travel 100 metres: the speed (km/hr) is 360 divided by the time in seconds.
Calculate the spray application rate: 600 divided by the swath width in metres multiplied by the output (litres/min) divided by the speed (km/hr).
Calculate amount of fertiliser you need to add to tank: the tank capacity (litres) multiplied by the fertiliser rate/ha (Kg) divided by the spray application rate (litres/ha).