Silage plays a crucial role in livestock farming in Northern Ireland, serving as the primary conserved forage for ruminants during the winter months and increasingly throughout the year. It provides a dependable and nutrient-rich feed source when fresh pasture is unavailable.
Set Targets
Good silage is dependent on the class of livestock you are feeding as what is good silage for high producing dairy cows is quite different to good silage for dry suckler cows. Quality targets should be set for the class of stock you intend to feed, and a plan put in place to hit these targets.
Grass feed quality based on cutting date:
| Date of cutting | 1st May | 8th May | 15th May | 22nd May | 29th May | 5th Jun |
| Grass yield (t DM/ha) | 2.92 | 3.99 | 4.98 | 5.96 | 6.79 | 7.82 |
| D-value | 75 | 73 | 71 | 69 | 65 | 61.5 |
| ME (MJ KG/DM) | 12 | 11.7 | 11.3 | 11.0 | 10.7 | 10.4 |
| Regrowth | Very fast | Fast | Good | Average | Average | Slow |
Nutrient Management
It is important to ensure the correct nutrients are applied to maximise silage yield and quality whilst protecting the environment. It is important that the nitrogen has been used by the crop before harvesting as too much nitrogen in the grass can inhibit fermentation resulting in poor quality silage. As a rule of thumb grass can use 2.5kg/ha (2 units/acre) per day. You can use this as a guide of when to apply nutrient to ensure the crop is suitable for harvest, be sure to include any organic fertilisers you may have applied in this calculation. Speak to your Fane Valley agronomist about fertiliser recommendations for your land.
Harvesting
Mow after the dew has dried off, A rapid wilt concentrates the sugars, allowing a quick and effective fermentation. A conditioner on the mower splits the grass, so there is a greater surface area for water loss. This can increase wilting speed by up to 20%.
Leave a stubble of at least 5cm to (7-8cm if multi-cut or red clover swards) allow air movement beneath the lying grass. Spread the crop quickly and over a wide area. Water loss is highest for the first two hours after cutting. Ensure rakes and tedders are set at the right height so they work efficiently and do not pick up soil or manure. Wilt as rapidly as possible ideally within 24 hours. Crops with high amounts of clover may need 48 hours. Row up into even ‘box-shaped’ swaths immediately before pick-up or baling.
Clamp Filling
Make sure the clamp has been thoroughly cleaned to avoid contamination which could inhibit fermentation. Best practice to use side sheets to ensure a good seal and prevent waste at edges this will also protect concrete.
When filling the clamp thin layers of grass at a maximum of 15cm and well consolidated throughout the filling process. This consolidation should be evenly throughout the filling process to ensure all air has been removed and reduce chance of slippage.
Seal the clamp immediately after filling, use a quality sheet and consider an oxygen barrier. Ensure the sheet is well weighted when sealing particularly around edges.
If you want to find out more about making quality grass silage, download our new silage guide here Silage-Guide-2025-WEB.pdf and contact your local Fane Valley Agronomist or call 028 9261 0485.
