Fertiliser is a costly commodity and farmers should aim to get the most out of it. With this in mind, fertiliser spreaders should be set up correctly. Every fertiliser spreader is different and it can sometimes be difficult to make sure you’re doing the right thing.
John McElvaney and Ger Griffin, Teagasc, put the attendance along the right track at the Precise Application of Fertilisers event held by the Fertilizer Association of Ireland recently.
The spreader should be level
Ger Griffin began by emphasising the importance of the spreader being level. If the spreader is not level, he said, it will be pointed into the ground on one side and cannot spread evenly. The lift arms of the tractor should be level and should be measured to ensure that this is the case.
That eliminates any issue with a concrete yard or a flat tyre. You know the machine is level with the tractor.
Wear and tear
Ger pointed out that wear and tear can have a big effect on your spread pattern. He added: “Rippling on the veins, where they are starting to wear, will start to have an impact on the spread quality or the evenness of spread.
“The distance that you’re spreading is dictated by how much fertiliser hits the disc and how much energy you can transfer from the disc to the granules of fertiliser.
It’s very important that the fertiliser can run along the disc without any friction.
While Ger acknowledged that a new set of veins can be expensive, the damage can also be costly if fertiliser isn’t being spread evenly.
“You could have everything else perfect; but if the vein is worn, it’s going to destroy your spread pattern – particularly where fertiliser is being thrown a long distance.”
A damaged vein. A hole has been made in the vein and cracks have developed
Spreading height
The spreader should be 75cm over the crop. This should be adjusted as the growing season moves on. For example, the spreader should be 75cm over a crop of grass or an emerging crop of spring barley; it should also be 75cm above a wheat crop at GS30.
Testing your spread pattern
Different manufacturers have varying methods of testing spread pattern.
“If you look at how little fertiliser is landing on the field, even at a high rate of application, you can see how important it is to have the spreader set up properly and to try and see what it’s doing across the field.”
A set of trays is inexpensive and gives a good indication of spread pattern. Inserts should be fitted to the trays, so the fertiliser stays within each tray. The trays should be laid out every 2m between bouts. Ensure that fertiliser is spread on each tramline covered by the trays.
The fertiliser should then be emptied from each tray individually into a test tube (as in the picture below). Alternatively the fertiliser from each tray can be weighed. The amount of fertiliser should be even across each tray.
