Multi-species swards outperform monocultures in Germinal Horizon trials

Thursday 25.07.2024 , News

From soil health to animal performance, multi-species swards can drive sustainable livestock production and Germinal Horizon has fresh insights to share from a four-year study.

Led by Dr Joanna Matthews, Technical Trials Manager at Germinal Horizon Wiltshire, the trials compared the performance of swards covering six mixtures. These included perennial ryegrass (PRG), PRG and clover, and four multi-species mixes comprising eight, nine, 14, and 16 components.

Building on previous research, practical insights were refined relating to seasonal yield, mixture formulation, nitrogen applications, environmental performance, and establishment timing.

Key findings

  • PRG yielded 35.4t DM/ha over four years.
    • PRG and white clover yielded 44.01t DM/ha.
    • A nine-component multi-species mixture yielded 47.1t DM/ha.
  • PRG ME was 10.69 MJ/kg over four years.
    • Clover ME was 11.49 MJ/kg.

Producing yield from spring to autumn

Germinal’s perennial ryegrasses form the backbone of the sward, bolstering early-season yields while legumes and most herbs are not actively growing – plantain is a notable exception.

Perennial ryegrasses, especially diploid varieties, are also effective at maintaining ground cover to prevent weed ingress. This is valuable because weeds can flourish in wet spring conditions, thus herbicide use can be decreased.

Finding the optimal blend of multi-species

The chart below illustrates how multi-species outperform monoculture grass leys. From June to September, the AberGreen plot was significantly outperformed on yield by the multi-species mixtures.

2021 seasonal yield profile

GHW - MSS 2021 Seasonal Yield Profile 1200x569 (1)

Note: Yield profile of a typical season

Having higher-yielding forage growing when perennial ryegrass enters its reproductive phase makes multi-species swards a game-changing forage for farmers.

Dr Matthews confirms: “Multi-species can bolster yields mid-season, even by just adding white clover.”

Over the four-year trial, PRG yielded 35.4t DM/ha whereas simply adding clover drove a 24.3% yield increase to 44.01t DM/ha. For comparison, the nine-component multi-species mixtures delivered a 33.1% yield increase to 47.1t DM/ha.

While monoculture leys are less productive, multi-species swards do have a sweet spot. This was evident from the 16-component multi-species mixture, which produced nearly 6t DM/ha less than the grass-clover mixture.

“As the number of components increases, the seasonal change in dominant species causes a contraction in yield.”

Less nitrogen is more cost-effective

Another major finding was that higher nitrogen applications were not cost-effective. At 250kg N/ha/year, the six mixtures only produced 4t more DM/ha on average versus 150kg N/ha/year – the natural rate of organic nitrogen application from grazing stock.

“This extra 100kg of nitrogen would not be cost-effective when it only returns 1t/DM per year,” Dr Matthews advises. “Furthermore, nitrogen impacted sward composition.

“Not surprisingly, we saw lower levels of clover when nitrogen was applied at higher rates, but higher levels of grass, chicory and plantain.”

Multi-species are resilient

“The research shows multi-species swards can make your grazing platform more resilient,” Dr Matthews explains.

Clover consistently delivered more energy and protein throughout the season over the four years (11.49 ME MJ/kg and 22.29% crude protein) compared to grass (at 10.69 ME MJ/kg and 20% CP).

GHZ - multi-species clover image 1200x800 (1)

“By incorporating clover, you will see a yield benefit and can underpin the quality of the sward while fixing nitrogen.”

Establishing multi-species swards

Although drilling later can be effective, Dr Matthews explains that herbs and legumes are “not quick out of the blocks” and should be established before winter when soil temperatures fall.

“Multi-species swards need to be established four to six weeks before your farm’s usual cut-off date for sowing grass,” Dr Matthews clarifies. Here are some other best practices that were identified in the four-year trial:

  • Understand your soil before choosing species: While Germinal’s multi-species grazing mixtures are suitable for most soil types, more diverse leys are only suitable for specific soils.
  • Set an objective before selecting a mixture: Perennial ryegrass provides early-season growth; clover naturally fixes nitrogen and is effective at finishing stock; herbs can support soil health and bolster first-year production.
  • Establishing multi-species swards: Sow multi-species into warm, moist conditions to let them establish before winter. Find our multi-species establishment guide here.
  • Nitrogen use efficiency: You can feed perennial ryegrass in spring but pull back after and let clover start fixing natural nitrogen from the environment.

Ask Germinal

Contact us today to discuss our research or to seek advice before establishing multi-species.