Tips on calibrating a fertiliser spreader

We all know how hard it is to apply fertilisers or selective herbicides to our lawn and in the past I have had to correct many an error for clients through their overdosing of the prize sward.

The problem does not have to be difficult to overcome but it does take a little thought.

Below I give a few tips on avoiding a costly mistake. Furthermore, the fear factor also means many people apply too little material to their lawn and the job just doesn't get done.

Application of granular fertiliser to the lawn.

Visiting the garden centre to buy your autumn fertiliser you will probably be offered the use of a small plastic drop spread with which to apply the material. However these primitive machines whilst effective in distributing the material cannot be relied on for accuracy.

So the best thing for you to do is calibrate the spreader yourself and it is not as daunting as you might think.

Now lets say that the instructions on the box or bag tell you to apply 35 grammes per square metre and you know that your lawn is 100 square metres; that's 3500 grammes or 3.5 kilograms that you have to apply. It is essential that this rate is applied exactly as stated to get best results.

Now this is the clever bit. Cut a piece of clear plastic at about 3 metres by three metres and lay it on a flat surface (i.e. your drive,patio or inside of your garage.

Cut a second piece of plastic 1 metre square and lay it in the middle of the larger piece in roughly the middle.

Make sure the gate to the spreader is closed.

Now measure out 3.5 kilos of material but add an extra .5 kilo because the spreader works better with weight in it. You can pour the excess back into the bag after..

Pour the material into the spreader and set the dial on the gate stop to the first setting. Walk over the plastic sheet up and down so that you have evenly covered the area. Close the gate and rest the spreader. Carefully fold the 1 metre plastic so that the material is caught in the fold of the plastic.

Pour the fertiliser into a small plastic bag and then weigh in your kitchen scales. This will then tell you how much material you have just applied to one square metre. You then have to repeat this process until you are within 5% +/- of the recommended application rate stated by the manufacturer.

This method is pretty fail safe and is effective with a rotary spreader but remember a rotary spreader like a cyclone will always throw the material out a little heavier on one side so you will have to take a view.

Please also read: Tips on herbicide Application and knapsack calibration