The agricultural sector is coming under increasing pressure to reduce its greenhouse gas emissions. According to Teagasc, agriculture accounts for 98% of ammonia emissions in Ireland, while land spreading of slurry accounts for almost half of this.

If Ireland is going to meet the obligations it signed up to as part of the Paris Agreement, we will have to slash our greenhouse gas emissions by 20% by 2020 and 30% by 2030. We analysed research carried out by Westphalian University of Applied Sciences in Germany. The university compared three different slurry application methods relative to the splash plate method in terms of the loss of ammonia (NH3) into the atmosphere within the first two hours after application.

They compared the dribble bar, trailing shoe and the disc injector relative to the splash plate method.

Disc injector

The graph shows that the best method to reduce ammonia losses was by using a disc injector. By using the disc injector, only 11% of ammonia was lost after application relative to the splash plate. This method involves using discs to slit the ground before depositing the slurry into these slits.

As the slurry is deposited into slits, it will have the least amount of exposure to air, reducing evaporation and the smell.

It must be noted that this method may not be suitable for all Irish soils.

In addition, this is the most costly of the four methods listed and requires significantly more tractor power to pull a slurry tanker while pulling a set of discs through the soil.

Trailing shoe

The trailing shoe is the second most effective application method, recording a 28% loss of ammonia relative to the splash plate. The coulter (shoe) separates the sward canopy and applies the slurry on to the soil surface, avoiding sward contamination. This way almost three-quarters of the ammonia is captured.

Dribble bar

The dribble bar had a slightly higher amount of ammonia lost (34%) in comparison to the trailing shoe (28%) relative to the splash plate. The reason behind this is that it deposits the slurry through the pipes situated above the crop, dropping the slurry both on to and in-between the crop canopy.