Top 3 Considerations When Buying a Slurry Applicator
Dribble bar, band spreader, trailing hose, trailing shoe, disc injector or shallow injection? Whatever name you read or see, they all refer to low emission spreading systems under evolving environmental regulations. The variety of systems available, and the number of options and features, can be baffling to even the most experienced farmer!
We have put together the top three factors to think about when considering a new slurry applicator. We understand every farm operates differently, so there is no one-size fits all approach. But, thinking carefully about these elements will help determine a solution that best fits you.
Farmer or contractor or both?
This is the first question we ask when talking about slurry applicators. For farmers to extract the most out of the slurry while staying compliant with emissions regulations, we also want to understand farming conditions including livestock, acreage, and current manure management practices.
For example, Michael Canny single-handedly runs a high-yielding herd of Holstein Friesians and followers on 200-acres in Co. Galway. Soil type is heavy clay and grass crops are heavy in this part of the country. He employs a traditional grazing system plus a zero-grazing regime sourced from between 40 and 60 acres on the farm, depending on yield. All waste and slurries are collected into a 200,000 gallon overhead lagoon system.
He uses a 3500-gallon Tandem Major tanker with 7m trailing shoe applicator to spread slurry back to the pastures. The trailing shoe applies slurry at the soil surface minimising sward contamination. Not only does this reduce ammonia emissions by 65% compared with 35% using the dribble bar (Note 1) but this method also improves grass yields by 21%, compared to 19% using the dribble bar. It also means stock can return back to land more quickly.
The precise time is dependent on a number of variables including rotation schedules, weather and ground conditions but stock can return to grazing as early as two weeks after application by trailing shoe compared with splash plate application
He can spread slurry back onto the grazed and zero-grazed pastures throughout the year. In general, he can give three or four applications at about 2,000-gallons per acre.
When you’re running a tight operation and trying to keep fertiliser costs to a minimum, these are significant savings in the long run.
What kind of ground?
Ground type should be the biggest concern for contractors. The kind of soil and topography of your clients will determine which system to choose. If the area is hilly and wet very often then a dribble bar will do just fine. You can still reduce ammonia emissions by 35% and improve grass yields by 19% (Note 1) (see chart).
The dribble bar system works well on both grassland and arable crop, while trailing shoe is often better suited for grassland. The trailing shoe is optimal to apply slurry in heavy clay soil and works well in grass longer than 8cm in height.
Disc injector or shallow injection has discs that cut into the ground surface and hoses deposit slurry directly into the slits. This is the best method of reducing ammonia losses with 99% reduction rate. It’s also best for retaining nutrients: 11 units of Nitrogen per 1000 gallons of slurry compared to 3 units of Nitrogen per 1000 gallons using a splash plate (Note 2). This translates to 25% improvement in grass yields.
However, a pitfall of shallow injection is it may not suit all soil types. Soil texture, stone content and ground contours limits its use. Also, this system requires greater tractor power to pull the discs through the ground. Disc injectors work best on short swards and place slurry 5-6cm below the surface.
Who is operating?
Another thing contractors (or anyone really) should acknowledge: the tractor driver. Contractors taking bookings from stressed out farmers with high covers might enlist extra help. The dribble bar is easier to operate so you’ve little to fear if you have a 17-year-old at the tractor wheel. If you reverse the tractor and forget to lift, you’ll bend the trailing shoe and pay a few hundred Euros to repair the damage. But with a dribble bar it’s not a worry.
The effectiveness of each technique will depend on slurry characteristics, application rates and weather conditions. For example, the trailing shoe method performs better if used following some grass growth, such as spring time application, rather than immediately on silage or grazing aftermath. Slurry injection under hot, dry conditions can cause grass scorching.
There are plenty of other factors to consider including macerator, work rate, and maintenance costs but these three areas should serve as the beginning point to decide which system best suits your operation. Our chart compares the three most popular systems on the market and their advantages.
- Webb, J., Pain, B., Bittman, S., Morgan, J., (2010), ‘The impacts of manure application methods on emissions of ammonia, nitrous oxide and on crop response—A review’, Agriculture, Ecosystems, and Environment, Volume 137, Issues 1-2, 15 April 2010, Pages 39-46. (https://www.afbini.gov.uk/publications)
- Teagasc. https://www.teagasc.ie/media/website/publications/2019/11.-Low-Emission-Slurry-Spreaders.pdf