A Vervaet Hydro Trike has brought a new dimension to the debate over low level slurry application which continues to rumble on as the laudable aim of reducing nitrogen loss runs into the practicalities of farming in less than ideal conditions.

Despite the various differences of opinion on the methods available, it has become accepted by advisory bodies that injecting the slurry into the ground is the best way to maximise the retention of nitrogen.

Setting the precedent

There is one contractor in Co. Kerry who has not only adopted this technique, but has become a keen advocate of the benefits it brings.

While it might be said that this is only to be expected of a business that has invested heavily in the appropriate machinery, the results do speak for themselves.

The contractor in question is Padraig O’Mahony of Castleisland who, last year, purchased a Dutch-built Vervaet Hydro Trike equipped with a 9.5m TBL injector boom that places 48 rows of slurry in one pass at a 20cm spacing.

TBL boom for slurry injection — The TBL Injector boom is also from the Netherlands. They are available in various configurations, this model has single discs and twinned elements to aid contour following

It was not bought as a new machine, it had been reconditioned by the manufacturer itself which has a team dedicated to the task of rebuilding its products, enabling it to offer them at a friendlier price with, it is claimed, all the reliability of a new unit.

The injection system itself comprises a disc which slices into the ground which is immediately followed by a blade that opens the slot into which a rubber boot discharges the slurry.

Slurry injection kerry — The disc cuts a slot which is opened by the blade, immediately following the blade is the boot which discharges the slurry into the slot. A round bar pinching the feed tube prevents flow when raised from the ground

Although the opening of the slit is done by disc, rather than knife or tine, the power requirement is still substantial and to cater for the draught, a 460hp Daf engine is installed to keep it all moving.

Charles O’Shea, who usually operates the machine, notes that although he hasn’t run up against the limit yet, he has come close enough to understand why they provide all those horses under the bonnet.

Power aplenty

The Vervaet Hydro Trike has a hydrostatic transmission powering the rear axle while drive to the single front wheel can be selected when required. Maximum road speed is 40km/h.

The tank has a capacity of 3,500 gallons (16,000L) and the weight is supported 1050/50 tyres at the rear and 1000/50 on the front.

To help with keeping soil compaction down, there is a Central Tyre Inflation system (CTIS) that has a reservoir built into the chassis and takes just seven minutes to fill the voluminous tyres from minimum to maximum pressure.

The Vogelsang pump and stone trap both fill the tanker and feed the distribution head

Filling the tank and feeding the slurry to the distribution head is done by a Vogelsang positive displacement pump, protected by a substantial stone trap.

This can be done via either a boom mounted behind the cab, or via a connection under the cab.

Slurry tanker Vervaet — The Vervaet may be filled from a nurse tank by a forward facing inlet mounted by the front wheel

This latter is especially useful when using a fleet of nurse tankers as it can empty them swiftly and so get on with injecting while the tankers do the transport part of the operation.

Constant rate with Vervaet

The disc/boot units are mounted in pairs and and are pressed to the ground by a spring, the pressure of which can be adjusted from the cab.

When the boom is raised the tubes feeding the boots are pinched closed hydraulically, ensuring that flow stops instantly.

Slurry injector Veraet — At 2,500 gallons per acre, there is very evidence that the field has been treated

In the field it all works well. On the day Agriland visited the slurry was being applied at around 2,500gal/ac, a rate which is automatically kept constant by a flow rate control valve linked to a ground speed sensor.

At this rate, on soil which was moist but not wet, there was evidence of where the slurry had been placed but there was no unabsorbed residue of material left on the surface as is found with either dribble bars or trailing shoe.

Multitude of benefits

Reducing nitrogen loss is the major reason given for switching to injection, but, according to Patrick, the benefits do not stop there.

To say that it is an odourless operation would be a little too optimistic, yet even the mix of cow and pig slurry being applied left only an impression in the field rather than a smell.

Cow slurry alone would most probably have been less perceptible still.

Slurry trike injector — The trike and injector can cope with gentle curves but requires lifting out at the headlands

The lack of runoff is another major advantage. With the slurry in the ground, rather than on top of it, it is not washed away into the nearest river as could happen with surface application.

The near absence of surface residue will also minimise any inclusion of slurry when cutting the next crop of silage, although leaving a slightly longer stubble than is often the case in Ireland will reduce this risk and bring quicker regrowth anyway.

Co Kerry O'Mahoney Vervaet — Joystick controls and ISOBUS screen look after the injection process while the pressure dials give instant indication of settings

Earlier grazing and cutting is also possible with the material safely out of the way.

There has been an instance of applying the slurry into a field where sheep were still grazing. Sheep, however, are far more selective than cattle so it is usual to allow at least a week to pass before cattle are turned back into the field.

Nitrogen where it is needed

As beneficial as these features are, the big advantage is that the nitrogen is applied directly to the rooting zone of the grass, giving it a tremendous boost according to farmers who have used the machine on their land.

The feedback from users is very similar to that of those who have switched to liquid fertiliser, which should come as no surprise as that is precisely what slurry is.

Filling the tank is quick and easy without the driver having to get out of the cab

Both groups talk of the speed of response to the treatment, the grass picks up and starts to get away within a day or two of receiving an application irrespective of the weather prevailing at the time.

Padraig notes that although nobody welcomes high fertiliser prices the increased cost has focused more minds on the value of slurry, which, he feels, is no bad thing.

Charles O’Shea (left) and Patrick Enright, who has become a keen advocate slurry injection now that he has seen the benefit of it on his land

Although it might be an exaggeration to describe him as an evangelist, Padraig is quite determined to see slurry being appreciated for what it is, a valuable resource that, if managed properly, can drastically reduce, and in some cases eliminate fertiliser costs completely.

Investing in the Vervaet Hydro Trike demonstrates his commitment to getting the management of slurry to be seen as an important part of a farming enterprise.

Irish farming is already starting to move in this direction and this latest development will give extra impetus to the shift in thinking.

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Nitrogen retention

Machinery Focus: Vervaet Hydro Trike slurry injection in Co. Kerry