Farmers reminded to use slurry additives with a ‘solid scientific backing’
Slurry additives can help reduce emissions, but farmers attending the Farming for a Better Future Open Day at Teagasc Johnstown Castle were told to only use slurry additives with a solid scientific backing.
Teagasc researchers reminded farmers that slurry is a valuable source of nutrients and can help to maintain soil fertility / health, but it also leads to methane and ammonia emissions during storage, and nitrous oxide and ammonia emissions during land spreading.
Attendees heard that the optimal use of slurry can help to reduce emissions and reduce chemical fertiliser use. Firstly, farmers were told of the benefits of low emission slurry spreading (LESS) – a proven technology that reduces ammonia emissions during spreading by reducing the surface area of the slurry on the land, thus allowing greater nitrogen availability to plants.
Additionally farmers were advised to check slurry dry matter prior to spreading using a slurry hydrometer, as this will give guideline nitrogen, phosphorus and potassium values for the slurry and allow farmers to adjust rates to align with crop requirements. Adjusting the rate of slurry application can also reduce emissions and make your slurry go further. Table 1 below shows how these nutrients can vary depending on slurry dry matter.
Table 1: Nutrients in cattle slurry presented by dry matter content
| Slurry dry matter (%) | N (units/1,000 gal) | P (units/1,000 gal) | K (units/1,000 gal) |
|---|---|---|---|
| 2 | 4 | 2 | 13 |
| 4 | 6 | 3 | 21 |
| 6 | 9 | 5 | 32 |
| 7 | 10 | 6 | 36 |
The topic of slurry additives was also broached with Teagasc researchers advising farmers to be selective when purchasing additives as most commercial slurry additives on the market today have no effect on emissions during storage and only additives that have a proven scientific backing should be used.
Solid-liquid separation of slurry – an option some farmers may be considering - was also highlighted as a method of reducing the volume of slurry stored. Further research will be carried out in Johnstown Castle on this subject in the future.
This article was adapted for use on Teagasc Daily from the paper and board presented by Shaun Connolly, Benjamin MaCartan and Dominika Krol titled: ‘Slurry Solutions: Reducing Emissions and Increasing Efficiency’ at the Farming for a Better Future Open Day.
Read more insights from the Farming for a Better Future Open Day here.
Also read: Journey to more sustainable farming showcased at Johnstown Castle Open Day