Multi-species leys can build resilience into grazing systems by not only maintaining growth throughout the season but also boosting crop yields.
That was just one of the positive reports headlined at the RABDF regenerative farming event, Down To Earth.
The event, staged at Grovenor Farms in Cheshire, revealed the results from Germinal Horizon’s grassland establishment trials and how various grazing regimes and nitrogen application rates affect persistency and yields.
Over the past four years, scientists at the company’s research facility in Melksham, Wiltshire, have been comparing the performance of six mixes: perennial ryegrass (PRG), PRG and clover, and four multi-species mixes containing eight, nine, 14 and 16 components.
The mixes have been trialled using two nitrogen fertiliser application rates of 250kg N/ha and 150kg N/ha.
Scientists found that perennial ryegrass (PRG) dominates early season yields when herbs are not actively growing, but multi-species come to the fore during the summer (June to September) when perennial ryegrass ‘shuts down’ under drought conditions.
PRG yielded 35.4t of dry matter per hectare over the four years. The simple addition of clover improved this by 8.61t, while using a multi-species and herb mix produced an extra 11.7t of DM/ha (to yield a total of 47t DM/ha) over the same period. This was comparable with the nine-component mix (see yield summary graph).
However, as multi-species swards became more complex, yield suffered – the 16-component was the lowest-yielding multi-species mix, growing almost 6t DM/ha less than grass and clover.
Dr Joanna Matthews, technical trials manager said: “Multi-species can bolster yields mid-season, even by just adding white clover.
“As the number of components increases, in later years, you are left with fewer primary herbs and the lower content of base grasses in the seed mix at establishment penalises yield.”
Higher nitrogen application rates (250kg of N/ha/year) only grew a total of 4t more over four years across the six mixtures, on average, compared to those that received 150kg of N/ha/year (mimicking the amount of organic nitrogen applied by grazing animals).
“This extra 100kg of nitrogen would not be cost-effective when it only returns 1t/year. 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,” explained Dr Matthews.
While later drilling can be effective, she said herbs and clovers are ‘not quick out of the blocks’ and must be established prior to the winter before soil temperatures drop.
“Multi-species swards need to be established 4-6 weeks before your usual cut-off date for sowing grass.”
In the first year, herbs were dominant in the eight and 14-species mixes, but they were largely overtaken by PRG and clover by year two, and by year four, plantain disappeared, and chicory levels fell dramatically.
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).
Multi-species offered higher protein and energy than grass, but they had more pronounced variations throughout the season and were lowest mid-season, when reproductive growth compromised energy.
Dr Matthews believes the research shows how multi-species can play an important role in helping farmers deal with extreme weather patterns caused by climate change.
“The research shows multi-species leys can make your grazing platform more resilient. By incorporating clover, you will see a yield benefit and can underpin the quality of the sward while fixing nitrogen.”
Key messages:
• Know your soils when choosing suitable species: Germinal’s multi-species grazing mixes are suitable to nearly all soil types, but more diverse leys will only be suitable to certain soils.
• Consider what you want to achieve before choosing components in a mix: Clover is a great source of energy for finishing animals and perennial ryegrass will provide early-season growth, but herb species can provide other benefits such as bolstering first-year production.
• Establishment: Sow herbs into warm, moist conditions so they establish well before winter.
• Use nitrogen efficiently to feed PRG in the spring and then allow clover to do its job.
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