How To Calibrate a Broadcast Spreader

Calibrating a spreader can be a tricky task. We have put together a 'how-to' guide to make the process simple. See our tips today.

What You Will Need:

• Broadcast Spreader
• Measuring jug
• Scales
• Either fertiliser or grass seed
• Flags or marker sticks
• Pen or pencil
• Tape measure (ideally 20-50m tape)

Pour your fertiliser into a jug and weigh on a set of scales how much you have making sure to make a note of this in grams. Then pour the fertiliser into the spreader making sure that the handle is in the shut position

Choose a setting on your spreader. Ideally you should do different tests on the lowest, mid-range and highest machine settings, to get a better idea on the range of spreading rates

Starting a small way back from the first marker, begin to walk towards the second marker at your normal walking speed, opening the handle and beginning to spread the fertiliser. Once you have reached the end marker, close off the handle and turn around and repeat the process back to the starting marker.

With your tape measure, measure the width of the product spread. It may be easier to do these steps on a hard surface with a sheet covering or tarpaulin as this will make it clearer to see the product (and collect it afterwards so there’s no wastage), rather than hunting in the grass.

Empty the remaining product from the spreader back into the jug and weigh the remains. The difference in weight from the amount in fertiliser you had before you started to spread to what you have left over is the amount of product you have used.

Completing the following calculations will then give you the amount of product needed per metres squared for that specific setting:

Step	What to Do	Formula	Example
1	Calculate the area covered	Broadcast width × Length	2.5 m × 40 m = 100 m²
2	Calculate the application rate	Product weight ÷ Area covered	1000 g ÷ 100 m² = 10 g/m²

Calculation	Formula
Area covered	Broadcast width (m) × Length (m)
Application rate	Product weight (g) ÷ Area covered (m²)