Multi-species swards – comprising mixes of grasses, legumes and herbs – are consistently out-performing perennial ryegrass (PRG) monocultures (receiving more than 200kg/N/ha), in ongoing research trials at University College Dublin (UCD) Lyons Estate.
Moreover, these multi-species swards are receiving 50% less nitrogen (N) than their PRG counterparts.
According to UCD’s Dr. Helen Sheridan, multi-species swards work on the basis of the different plant types combining to make optimal use of the resources contained within the soil.
Multi-species swards and climate change
Sheridan spoke at an Agricultural Science Association (ASA) webinar earlier this week. The event was held in association with Germinal Ireland.
She explained that multi-species swards have a role to play in allowing Irish agriculture meet its climate change obligations. They can also be utilised to significantly improve water quality.
She commented: “Multi-species grasslands are not to be confused with species-rich grasslands. These are highly productive swards, with the capability of driving high levels of output.
“Swards can contain up to 10 species. But they are grown for their agricultural productivity primarily.
“Our work in this area commenced with the SmartGrass programme, which got underway in 2013.
“The work centred on the management of trial plots, containing up to nine different forage species. The control was a pure PRG sward receiving 250kg/N/ha.
“All plots were harvested eight times throughout the growing season.”
Results of trial
According to Sheridan, a number of the multi-species mixes out-performed the PRG control, even when zero N was applied to the trial plots.
“The legume content of the swards was driving production,” she explained.
Subsequent animal trials with breeding sheep and lambs confirmed the benefits of the multi-species swards from a production point of view.
“Lambs were finished two weeks earlier relative to those maintained on PRG-only pastures,” Sheridan commented.
The UCD trial also highlighted the health benefits that can be delivered courtesy of sheep grazing multi-species swards.
Animals on these pastures required fewer anthelmentic treatments throughout the grazing season.
The impact of multi-species swards on calf-to-beef output is currently being investigated as part of UCD’s long term grazing platform project.
The research work got underway in 2019. It has involved the establishment of three farmlets (8ha each), each with a different sward type: pure PRG; a PRG/white clover mix; and a multi-species sward comprising PRG, Timothy, white clover red clover, chickory and ribwort plantain.
To date this work is showing that multi-species swards can help secure improved growth rates, averaging an extra 200g/head/day.
Cattle grazing these pastures can also be finished a fortnight earlier than their counterparts on pure PRG swards.