Farm Ireland

Thursday 24 May 2018

Don't lose track in slurry season

SUITABILITY: Much higher work rates are achievable with umbilical slurry spreading systems but thereare limitations, chiefly that the layout of the farm must be suitable.
SUITABILITY: Much higher work rates are achievable with umbilical slurry spreading systems but thereare limitations, chiefly that the layout of the farm must be suitable.
TRAILING SHOE APPLICATION: the benefits over the splash plate in terms of reduced ammonia losses are negligible for spring spreading, but there are clear advantages in terms of a speedier return to grazing
Des Cunningham and his son Roy.
Derek Casey

Derek Casey

Once again our weather has made a mockery of the slurry spreading dates. Only in the last 10 days or so has it been possible to get some slurry out without doing serious ground damage.

The case for a flexible year-by-year decision on spreading dates is surely stronger than ever.

Can there be any reasonable argument against such an approach?

Contractors I spoke to this week say they have been getting calls from anxious farmer customers looking to get slurry out. In a lot of cases farmers are only able to consider the driest fields in the farm for now – the idea being to buy some time and make space in slatted tanks.

This is awkward and expensive on both farmer and contractor as it means having to get machines back for a second or even third time to finish the job. But it's the right thing to do to prevent rutting of the ground and getting bogged down in fields that are just still too wet to travel on.

The temptation might be there to spread and be damned, but the consequences in terms of compaction will be felt long after this spring. Those unlucky enough to not have even one field suitable for travelling on yet have resorted to moving slurry from one slatted tank to another in desperate bid to make space.

The good news is that, when conditions are suitable for spreading, machinery options for slurry equipment have never been better. A lot of contractors offer a couple of different systems ranging from splash plate to injection, umbilical spreading or trailing shoe application.

After all the rain of recent weeks, the one constant that must be considered irrespective of the system used is tyre ground pressure. Whether you are spreading with your own tanker or getting a contractor in, be sure to adjust tyre pressure accordingly so the least damage possible is done.

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Make common sense decisions: does your contractor have a tandem-axle tanker rather than a single-axle tanker? This will help spread the weight of the load.

Apart from the number of axles used, in recent years some Irish manufacturers have been at the forefront of developing other techniques for reducing soil damage.

A good example is Tipperary-based Abbey Machinery's weight management system, available on either tandem or tri-axle tankers. This feature works with a separate compartment at the front of the tanker which, as the tanker empties, remains full.

Only when the tanker's rear compartment drops to a certain level will the front compartment empty. The design ensures weight is kept on the tractor's drawbar for longer, allowing for better traction, even towards the end of a load of slurry. Wheel slip is minimised.

Most slurry application in Ireland is carried out using splash plate tankers. This method of application serves farmers well for a number of reasons. It has efficient work rates, simplicity of technology, minimal machine downtime and relatively low cost. The only restriction to slurry application using the splash plate system in Ireland is that the machine must be fitted with a low trajectory splash plate. It is a system probably best suited for spreading on low covers.

On the downside, the return to grazing time (approximately six weeks) is longer than for the equivalent trailing shoe machine (approximately two to three weeks). This is because the splash plate tends to cover the grass in slurry, whereas the shoe places the slurry closer to the grass roots where it is taken up faster.

Ammonia losses – a summer concern

In the recent past there has been a slight shift towards alternative application methods, mainly due to the high level of gaseous ammonia losses associated with splash plate application.

Ammonia is a compound that contains nitrogen. Approximately 50pc of the total nitrogen contained in slurry is present in ammonia form. While this form of nitrogen can be taken up quickly by crops, it can also be volatilised into the air and lost.

Teagasc trials have shown that losses of ammonia to the air are at their highest in the 24-hour period immediately after slurry application, with the initial six-hour period being most critical.

Losses of ammonia are caused by weather conditions that cause drying of the slurry, particularly warm, dry and sunny conditions (a problem many would only love to have at this time of year).

Ammonia losses with splash plate application can be reduced by applying in weather conditions that will not cause excessive drying. While heavy rainfall and saturated soils must be avoided, application on days that are cool, overcast or even misty are recommended.

The alternative application methods available are collectively known as 'low-emission' methods, so-called as they are designed to reduce the gaseous emissions of ammonia. The principle is that the slurry is applied in lines rather than as a thin film.

All low emission methods distribute slurry through a set of pipes that are mounted on a boom at the rear of the machine. The most common alternative methods available are bandspreading, trailing shoe and shallow injection.

Costing decisions

The costs and benefits for a farmer of switching to a low emission method of slurry application will need to be assessed on an individual basis. The beauty of hiring a contractor is that you can dip your toe in the water, try some of the new technology on offer and see if it works for you.

For applications to grassland, the aim is always to apply as much slurry as possible (70pc is a good target) in the spring. That seems hard to achieve in a year like this where the ground is soft, but a good fortnight can change everything as last year proved.

Where this can be achieved using the splash plate method, the Teagasc research mentioned earlier has shown that any advantages to nitrogen utilisation from using a low emission method will be small.

By reducing grass contamination, the low emission methods allow application of slurry into taller swards with minimal grass contamination. This may help to increase the amount of slurry applied in spring and it is certainly an option for farmers who might be in trouble with high covers at the moment.

In years like this the debate over ammonia losses is often superseded by the more burning question for farmers of how to get the job done and make space in tanks without causing significant ground damage.

Another method of application, umbilical spreading, may have the answer for the wettest of ground. With this system slurry is pumped down a special high pressure hose from the slatted tank to the field, where it is distributed using an umbilical spreader.

The system's attractive combination of low ground pressures (no field tanker is used) and high output (up to 25,000 gallons an hour) are often just what the doctor ordered for wetter farms that have reached capacity in terms of slurry storage. However, umbilical spreading may not work for a farm that is fragmented; the ideal farm for this system is one land block with a central slurry storage point.

Contractors' reporting stop start season

1. Adrian Elliot, Athlone, Co Westmeath

A few years ago Mr Elliot bought a new Cross 3,000 gallon single-axle tanker with a 7.6m Bomech trailing shoe applicator for €45,000. It took farmers a little while to get used to the new machine, but once they saw how quickly cattle could get back grazing compared to ground that had received slurry from a traditional splash plate spreader, Mr Elliot started to get plenty of business.

"The winter has been a bit stressful for farmers because covers went quite high late into the back end of the year," Mr Elliot explained.

"Then, all of a sudden, we had all the wet weather and tanks filled up very quickly between slurry, run off and soiled water.

"I have had a lot of bookings from farmers with high covers since the New Year who know that the trailing shoe system can get the slurry right in around the grass roots where it will be utilised best.

"They don't want the grass covered in slurry. But it's a lottery with the weather at the moment, we can only take it day by day."

2. Des Cunningham, Carrickmacross, Co Monaghan

In 2008 Mr Cunningham and his son, Roy, invested in an impressive 3,000 gallon self-propelled Terragator spreader. This machine uses the shallow injection method of application and has the ability to crab steer in order to reduce ground compaction. The disc injector is 7.7m wide and consists of 42 discs at 15cm intervals. The injector works by using the discs to cut a slot into the ground about two inches deep. Rubber placers, which immediately follow the discs, then put the slurry into these slots.

Mr Cunningham says some of his customers are taking last-ditch measures to ensure cattle are not left standing in slurry.

"I had to shift slurry from one slatted tank to another for one of my customers last week – our initial plan was to get out spreading but when we inspected the field we knew it just wasn't up to it.

"It could be a case of going back two or three times and spreading on the fields that are driest first. This isn't ideal for the farmer or myself, of course, but it's the only way to do it this year."

Irish Independent