It is a tempting scenario – the fertiliser spreader is past its best and the sprayer sits temptingly in the yard.

So why not make the switch to liquid fertiliser and gain increased accuracy in application?

Well it’s not quite as simple as it seems says Rob Starkey, Chafer Machinery’s sales manager.

“On the face of it, using your sprayer to apply liquid fertiliser can be a good idea, but there are several things to consider before ordering a few thousand litres of product,” he explains.

Mr Starkey says that most sprayers on the market are capable of applying liquid fertilisers, although there are several aspects to consider and check on your machine before going ahead.

“Typically, application rates can be up to 1000 litres/ha (405 litres/acre), and higher volumes will mean more time is spent filling the sprayer and forward speeds may have to be reduced considerably to achieve the recommended rate,” he says.

Sprayers with piston diaphragm pumps simply lack pump volume and flow to be able to fill a spray tank quickly – and it’s the same when applying product in the field.

“Sprayers with centrifugal pumps offer much higher performance, and an increased work rate,” he says.

“Our own sprayer range, for example, which has been developed to apply liquid fertiliser, has pump capacities that offer flow rates of 650 litres/min at 10 bar pressure.

“Operators will need to be prepared to reduce forward speeds to be able to apply enough volume, and this means output will be reduced considerably when compared to spraying,” he says.

He also warns that flat fan sprayer nozzles can scorch the crop particularly with liquid nitrogen.

“To reduce the risk of leaf burn, it’s important to equip the sprayer with umbrella jets or dribble bars, that produce a larger droplet and put the liquid where it’s needed rather than wash the crop canopy with a fine mist,” he says.

The firm’s Streambars, for example, simply fit onto a sprayer’s nozzle holder to create a vertical stream of liquid that drops to the ground.

Interchangeable, colour-coded restrictors allow flow rates to be adjusted to cover a range of nitrogen applications.

The price of each bar – which carries four outlets and covers a 50cm section of boom – is 5.70.

For those who brave the changes and make the move to liquid, there are considerable benefits to be had.

There are no longer any bulk bag disposal issues, and using a sprayer offers increased accuracy of application over the full working width.

As a result, it is possible to put fertiliser on in much windier conditions than would be possible with a twin disc spreader.

“A sprayer will provide a more consistent pattern over the full working width, which means there’s less risk of striping – unless a nozzle blockage occurs – and so the potential for yield detriment is also removed,” he adds.

Despite the advantages, liquid fertiliser storage remains an issue.

“You have to consider either buying or leasing bulk storage tanks, and of course their strategic location around the farm to solve logistical issues,” he says.

“And these can include easy access for delivery trucks in addition to convenience for refilling the sprayer.”

Perhaps the biggest issue of all, he says, is corrosion.

“Liquid fertiliser is highly corrosive and will eat its way through equipment at a considerable pace,” says Mr Starkey.

“Unless you’ve got stainless steel spray tanks and lines, you need to be prepared to get the power washer out on an almost daily basis.”

fwmachinery@rbi.co.uk