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JULY 2019
www.irishfarmersmonthly.com
Education
19
The SMART approach
A new plot of land purchased by UCD is now a site of global importance for research that will be
undertaken here to address many of the challenges facing ruminant production. This month sees
the swards being sown. Here, we talk to Dr Helen Sheridan, of the School of Agriculture and Food
Science, UCD, about the importance of this long-term grassland experiment at UCD Lyons Farm.
In 2012 UCD, Teagasc and AFBI joined together to
secure funding for the SMARTGRASS project: a four-year
research project funded by DAFM, to examine alternative
swards to perennial ryegrass. "We have all of these grasses
that occur in Ireland 135 species and yet we focus on
one particular species; perennial ryegrass. And there is
good reason why we do: it is highly digestible when it is
managed correctly; it recovers well following defoliation
so you can graze it again and again; and it is very
productive. But it is only productive if you keep putting
nitrogen on it. We wanted to see if there was anything
we could do to reduce our reliance on fertilizer nitrogen,
given that it increases the potential for environmental
pollution, nitrous oxide emissions, loss of biodiversity,
and also represents a very significant direct cost to
farmers."
Looking to the past
The team was interested in looking at older literature,
which showed benefits of different species in grassland,
before the use of agrochemicals came to the fore. "We
wanted to look at alternative sward types and see how
they might respond in terms of lower nutrient input
levels versus a high input perennial ryegrass sward; not
necessarily to see if they could be better in terms of yield
but to see could they even be in a reasonable positioning
so that you could say `okay, I am down one ton of dry
matter but I have made up for that in terms of the reduced
amount of fertilizer I have put on'. But what we found
was very interesting: we tested a range of sward types and
for those that contained at least 30 per cent legume we
could get the same or greater dry matter yield out at 90kg/
ha of fertilizer nitrogen versus our ryegrass monoculture
getting 250kg/ha of fertilizer nitrogen. That was at small
plot level and what we had chosen were three different
functional groups: grasses, legumes and forage herbs
(species like chicory and ribwort plantain). My colleagues
took the best range of sward types high input ryegrass
monoculture; ryegrass and white clover; a six-species mix;
and a nine-species mix and established a farmlet scale
experiment on Lyons Farm and grazed those swards with
sheep and their lambs."
The results
The results were hugely positive in favour of the multi-
species mixes and in particular the six species mix.
"Doctors Bridget Lynch, Cornelia Grace and Associate
Professor Tommy Boland found that the ewes and lambs
performed very well on the mixed swards: lambs matured
two weeks earlier when comparing to a ryegrass sward.
And, importantly, they seem to have a reduced reliance for
antihelminthic usage; so, the worm burden on the lambs
on the multi species swards was reduced. Given that we
are facing such a problem with antihelminthic resistance,
this is hugely important."
In addition, the ewes showed better body condition scores
at key points in the lifecycle, "so this showed that the
lambs weren't benefiting to the detriment of the dams".
Helen continues: "Colleagues also found a much lower
estimated nitrous oxide emission per ton of dry matter
produced from our multi-species swards and we also
found significant benefits for invertebrate communities
(above and below ground) in the lower input, more
diverse swards."
Long-term commitment
Helen notes that while the results showed much potential
for the positive benefits of the multi-grass sward, it
remains challenging considering there is still much to
learn with regard to their management. "Most research in
production grassland has been around perennial ryegrass
for the last 60 years or so, so we know how to manage
that. We are now trying to relearn some of the more
complex ways of managing grassland. We have to look at
what the ecological requirements of each species are and
then come up with management practices that will try to
facilitate all of them in terms of their persistence in the
sward."
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