Get the financial benefits of reseeding grassland

Forage production and livestock performance go hand in hand. This is why reseeding older and less productive pasture is fundamental to effective grassland management, explains Germinal expert Paul Morgan.

Being ready to take advantage of any good weather windows next spring will help you realise the financial benefits of reseeding grassland.

Pasture becomes less productive over time

A seven-year study at Scotland’s Rural College (SRUC) found that perennial ryegrass yields fall over time. Researcher David Lawson discovered that yield decreased by 50% in some cases, with all varieties impacted. However, relatively high production can be maintained in the first four years before a noticeable dip occurs.

Yield of late perennial ryegrass varieties, 2014-21

Source: David Lawson, SRUC

Grass yield impacted by weed ingress

Declining yield is not just caused by ageing pasture but also weed ingress. In the graph below, research from the Institute of Biological, Environmental, and Rural Sciences (IBERS) at Aberystwyth University, shows that weeds start to take over by years four and five after reseeding if they aren’t managed.

Perennial ryegrass content versus weed species over 10 years

Source: IBERS

With effective grassland weed control, you can work to maximise PRG content. However, it is a challenge and production can be impacted if just 10% of a ley contains weed species.

Lower quality in meadow grasses

Over time, perennial ryegrass can be replaced in leys when weed grasses ingress. Examples include Yorkshire fog, Rough stalked meadow grass (RSMG), and Smooth stalked meadow grass (SSMG).

Below, this is a problem because D-value drops when comparing PRG with weed grasses. These are unpalatable, low-yielding, and less effective for nitrogen use efficiency.

The quality of sown grasses vs meadow grasses

Source: 2023/24 Recommended Grass and Clover List

Can you afford not to reseed grassland?

Further research from IBERS shows the difference between new leys with 95% perennial ryegrass (PRG), older leys (70% PRG), and permanent pasture (50% PRG).

Unfortunately, the loss of metabolisable energy (ME) in older leys can hinder milk and meat production from grass. The table below shows that lost meat and milk can cost thousands. This is the reality if lost forage potential isn’t replaced.

Lost production potential when comparing different leys

Source: IBERS

You could try using concentrate to make up the shortfall. However, concentrates can cost £360 per tonne of DM compared with £80 for grazed grass. And the table above shows just how expensive it is to use concentrate as a replacement for lost forage production.

The 5 benefits of reseeding grassland with Germinal varieties

1. Aber High Sugar Grasses (HSG) improve protein use efficiency to drive liveweight gain by 20% and milk production by 6%.
2. By capturing more protein, Aber HSG varieties emit less ammonia and nitrous oxide.
3. Incorporating clover can enable swards to fix 150kg of Nitrogen per hectare per year, reducing fertiliser costs.
4. Using white clover can provide 27% crude protein.
5. Germinal red clovers last 4-5 years compared to 2-3 for traditional clovers. Red clovers can also lift grass silage quality from 12-14% protein to 16-20%, reducing supplementation requirements

Tip: For advice, view our full guide on reseeding grassland.

Ask the forage experts

Contact your local Germinal expert to discuss mixture options to boost your forage performance in 2025.

William Fleming, Area Sales Manager (Scotland, Northeast England)

T: 07971640428

E: [email protected]

Paul Morgan, Area Sales Manager (Southern England, South Wales)

T: 07713 878069

E: [email protected]

Harley Brown-Keech, Area Sales Manager (Central England, North Wales)

T: 07880469645

E: [email protected]