DETERMINE WATER RATE
Step 1: measure out an area of 10m x 10m square ( this equals a total of 100 square metres)
Step 2: Fill your sprayer with a known amount of plain water ( say10 litres) - do not add weed killer at this point
Step 3: At your usual speed and rhythm, spray the area to evenly apply spray. The ground or target vegetation should be thoroughly wetted but not excessively to cause saturation or runoff.
Step 4: When finished, top up the sprayer to the original level, noting how much water is used to bring the tank back to the starting level. ( for the purpose of this example lets assume this amount in 2 litres)
Step 5: As most herbicide labels state the rate in litres or grams of product per hectare, we now will need to calculate how many litres per hectare ( 10, 000 sq metres) we are applying with our sprayer.
multiply the amount of water used x 100 ( because there are one hundred lots of 100 square metres in a hectare)
ie 2 litres x100 = 200 Litres per hectare
DETERMINE CORRECT WEED KILLER RATE TO MIX
Step 6: Read the product label and determine the rate of weed killer to be used per hectare ( let's say for this example it is 5 litres per hectare)
Step 7: So you would add 5 litres per 200L if your spray tank holds 10 litres add 250mls per 10 litres
(nb this is the same ratio as 5 litres per 200 litres of water)
HOW TO SPRAY
Step 8: Now go spraying maintaining the same speed and rhythm as before
Easy!