ABS59351

The Effect of Multispecies Swards on CO2 and N2O Emissions


  • Oral Presentation
  • Climate Change and Sustainable Land Use
  • 11 Jun 2018 15:25
  • FS-G01, UCD Agriculture and food science Centre
  • View all IPSAM abstracts

Bruce A. Osborne
School of Biology and Environmental Sciences, University College Dublin
Earth Institute, University College Dublin

Laura Gallego Lorenzo*
School of Biology and Environmental Sciences, University College Dublin
Earth Institute, University College Dublin

*Presenting Author


Ireland has the long-term objective of growing its beef and dairy industry so there will be an increasing demand for forage. At the same time, Ireland has to meet its EU greenhouse gases (GHG) emissions targets so the challenge is to enhance grassland productivity whilst also reducing GHG emissions. Given that multispecies swards can have higher biomass production compared to perennial ryegrass monocultures with lower inputs of nitrogen (N) they might fulfil both purposes. To examine this, measurements of nitrous oxide (N2O) and carbon dioxide (CO2) emissions were made from a 4-year-old grassland experiment at the Smart Grass experiment in Lyons Estate Research Farm, Newcastle, Co. Dublin. The Replicate Design experiment consists of four pasture mixtures ranging from a monoculture of a single species to a complex sward of nine species (three grasses, three legumes and three herbs) with different fertilizer treatments (0-200 kg N ha-1y-1). Measurements of GHG fluxes were conducted from April to November 2017 with a photoacoustic gas analyser. The results showed that increasing species number lead to higher yields and more efficient N use, showing mixtures lower emissions factors (N2O emissions/N applied) than monocultures at the same fertilizer rate. The more relevant GHG emissions triggering factors were soil moisture and temperature and the strongest relationship with ryegrass monocultures, suggesting that monocultures are less resilient to future climatic conditions. Thus, multispecies swards can be used to optimize production and be resilient to future climate conditions given that there were less N losses (by N2O emissions or by leaching) and the forage productivity was not compromised.