Dr Deirdre Hennessy is a Lecturer in Sustainable Agriculture (Grassland) in the School of Biological, Earth and Environmental Sciences at University College Cork. Deirdre is a Co-Principle Investigator in the RI funded VistaMilk Research Centre. She is Senior Editor Irish Journal of Agricultural & Food Research. Deirdre Chairs the European Grassland Federation Grazing working group and is a member of the European Grassland Federation Executive Committee. Deirdre joined UCC in 2023 under the UCC Sustainable Futures programme. Prior to joining UCC, she was a Senior Research Officer in the Grassland Department at Teagasc Moorepark. Deirdre is a Past President (and first female President) of the Irish Grassand Association (2012-2013).

My research interests include incorporation of white clover into grazed grassland swards, perennial ryegrass and white clover agronomy, nitrogen use efficiency, grass growth, and pasture image analyses. 

I have a number of ongoing and past research grants:

• GrassWise - Horizon Europe (2026-2030) - WP4 Leader
• Research Ireland VistaMIlk Research Centre (2024-2030) - Co-PI and Pasture Theme Lead
• ClieNFarms - Horizon 2020 (2022-2025) - WP3 Leader
• Led the Teagasc research programme which showed that using white clover in grazed swards can reduce nitrogen fertiliser application in grazing systems by 100 kg N/ha. This led to the Department of Agriculture, Food and the Marine introducing the condition that farmers in derogation must include white clover in all new reseeds.
• Principal Investigator of the DAFM-funded Research Stimulus Fund project ‘Modelling for Increased Grazing Management Precision on Irish Grassland Farms’ (Grant no. 11/S/132). A key outcome of that project was the development of the MoSt grass growth model, which is used by Teagasc to provide weekly grass growth predictions for farms across Ireland. These predictions are widely published, including in the Grass10 newsletter, the Irish Farmers Journal, and the Met Éireann Farming Forecast on RTÉ 1 every Sunday.
• Led the multidisciplinary ‘Grass to Milk’ research project at Teagasc, which developed key indicators for grass-fed milk. This research is used by Ornua in marketing Irish pasture-fed milk and milk products.
• Collected the grassland images and associated measurement data in the Irish Grass Clover Dataset (VistaMilk), which has been made available through Zenodo.

• Hannah Irish (2021-2026) Thesis title: Increased understanding of the role of N fertilizer in grass-white clover milk production systems
• Neil Kennedy (2024-2029) Thesis title: Exploring the influence of the soil microbiome on rhizobia infection of white clover nodules
• Robert Serem (2024 - 2027) Thesis title: Effect of grazing management on tropical grass production and quality
• Lucia Gil (2025 - 2029) Thesis title: Precision nitrogen management for perennial ryegrass/white clover swards to improve grazing dairy systems sustainability
• Emily Cassells (2025-2029) Thesis title: Evaluating techniques to estimate dry matter intake of dairy cows grazing diverse swards

• Ellen FitzPatrick (2018-2022)
• MaryAnne Hurley (2016-2020)
• Stephen McAuliffe (2014-2019)
• Jack McDonnell (2014-2018)
• Michael Egan (2011-2015)
• Daniel Enriquez-Hidalgo (2010-2014)
• Christina Hurtado-Uria (2008-2013)
• PJ O'Connor (2008-2012)
• Willie Ryan (2006-2011)

My teaching activities centre around Grass and Forage Production, Grassland Management, Sustainable Agriculture, and Communication