The use of multi-species swards lowers the levels of nitrogen (N) fertiliser application on farms by at least 60%, according to a new study.
The research from University College Dublin’s (UCD’s) School of Agriculture and Food Science compared the effectiveness of multi-species swards when compared to the typical swards sown on many Irish dairy and beef farms.
Multi-species swards consist of a variety of plants from different families including clovers, grasses, brassicas and herbs.
The work in UCD has focused on a six-species sward containing two grasses, two legumes and two herbs.
Multi-species swards
Along with a significant reduction in N use, the researchers found there was a huge increase in the amount of fodder grown when this type of sward is used.
Initial findings have shown that specific types of multi-species swards can produce up to 25% more herbage for cattle.
If the new findings are applied to a typical 100ac farm it means that a farmer could grow an extra 100t of dry matter feed while spreading 4,600kg less N over a year.
Cattle consuming this multi-species sward reached their target slaughter weight approximately five to six weeks earlier than their counterparts grazing a perennial ryegrass monoculture.
The researchers said this means that the carbon footprint per kilogramme of beef produced is 15% lower.
Additional benefits recorded on these swards include enhanced earthworm diversity and activity, increased water infiltration rates and enhanced invertebrate diversity.
Study
The ongoing research is being supervised by Prof. Tommy Boland in UCD’s Lyons Farm on the Dublin-Kildare border, along with his colleagues Assoc. Prof. Helen Sheridan and Dr. Alan Kelly.
To date, the study has been focused mainly on beef systems, but positive results have also been recorded in dairy and sheep trials.
“Irish agriculture is faced with important targets to enhance the environmental sustainability of the food we produce
“These include reducing greenhouse gas (GHG) emissions by 25% by 2030, reducing the quantity of fertiliser nitrogen we apply and improving water quality and biodiversity in our farmed and wider landscapes,” Prof. Boland said.
“But in making these changes we need to be conscious of the economic and social sustainability of our farming practices also,” he added.
“Irish agriculture is dominated by pasture-based livestock production systems. And these systems haven’t developed by accident.
“They have developed in response to our geographical and climatic advantages for growing and grazing grass, and also in response to national and European agri-food policy,” he said.
Although the research on multi-species swards is still in its infancy, Boland said that it is showing “consistent positive findings”.
“I am confident that when we grow multispecies swards and feed them to beef cattle and sheep, we improve animal performance, and we grow that feed from substantially lower levels of fertiliser inputs and as a result increase farm profitability.
“There are many additional benefits and while we need to continue research into this area the future direction must also include plans to support farmers who want to use these swards in doing so, he said.
The research will be among a number of studies that will be discussed at the Agricultural Science Association (ASA) annual conference in September, as part of a series of debates on the science of sustainable food systems.