White clover-based grazed grassland in Ireland

Grassland type Permanent

Name of practice White clover-based grazed grassland in Ireland

Name of main actor Teagasc (The Irish agriculture and food development authority)

Type of actor(s) Farmers

Location Ireland

Agro-ecological region Temperate

Sustainability dimension involved Environmental, Economic

Sustainability sub-themes Atmosphere, Water, Biodiversity, Materials and Energy, Decent Livelihood

Year of implementation 2002

Description of best practice A ruminant production system that balances low fertilizer nitrogen (N) use with high productivity and farm profitability from grazed grassland. The use of white clover for biological N fixation, limiting fertilizer N use to springtime-only, correct grazing management, efficient use of slurry and selection of livestock with appropriate genetics are the key best management practices within this system.

Outcomes and impacts Management practices that promote and sustain herbage production from clover-based grassland have been identified (Humphreys & Lawless, 2008; Phelan, 2013). Oversowing (broadcasting) clover seed, reducing fertilizer N input, low (4 cm post-grazing height) and a long grazing season all promoted clover content, clover herbage production and biological N fixation (Phelan et al., 2013a; 2013b; 2014). The farm profitability of dairy production based on N fertilized grass-only (FN) and grass with white clover (WC) was assessed using ten years of data from Solohead research farm and a range of milk and fertilizer prices (Humphreys et al. 2012). Stocking density, milk and total sales from WC were approximately 90 % of FN. Therefore, FN tended to be more profitable when milk price was high and fertilizer N price was low, as was the case between 1990 and 2005. However, the increase in fertilizer N price, and fluctuations in milk price since 2005 have resulted in the profitability of WC being equal to, or higher than, FN in recent years. Total greenhouse gas emissions from the WC system was found to be 11-23% lower than that from FN when measured using life cycle analysis (Yan et al., 2013). Nitrate (NO3-) leaching to groundwater from the WC was found to be extremely low (average of 0.33 mg NO3- N/l) and was consistently found to be well below the maximum allowable concentration (11.3 mg NO3- N/l) set by the EU water framework directive (Necpalova et al., 2012). In summary, the white-clover based grassland system at Teagasc Solohead research farm can substantially reduce the environmental impact of ruminant production in Ireland with potential to maintaining, or increasing, farm profitability in recent years (depending on the price of fertilizer relative to farm product). References: Humphreys, J. & Lawless, A. 2008. A guide to the management of white clover in grassland. Moorepark Dairy Research Update Series No. 3. Teagasc, Oak Park, Co. Carlow, Ireland http://www.agresearch.teagasc.ie/moorepark/Publications/pdfs/MPK%20Dairy%20Levy%20Update%20Series%203.pdf Humphreys, J., Mihailescu, E. & Casey, I. A. (2012). An economic comparison of systems of dairy production based on N fertilized grass and grass-white clover grassland in a moist maritime environment. Grass and Forage Science 67: 519-525. Necpalova, M., Fenton, O., Casey, I., & Humphreys, J. (2012). N leaching to groundwater from dairy production involving grazing over the winter on a clay-loam soil. Science of the Total Environment 432: 159-172. Phelan, P. (2013). Aspects of grazing management to improve productivity and persistence of white clover in Irish grassland. PhD Thesis, Waterford Institute of Technology, Waterford, Ireland. 312 pp. http://repository.wit.ie/2669/1/Paul%20Phelan%20Thesis.pdf. Phelan, P., Casey, I. A., & Humphreys, J. (2013a). The effect of target postgrazing height on sward clover content, herbage yield, and dairy production from grass-white clover pasture. Journal of dairy science, 96(3), 1598-1611. Phelan, P., Keogh, B., Casey, I. A., Necpalova, M., & Humphreys, J. (2013b). The effects of treading by dairy cows on soil properties and herbage production for three white clover‐based grazing systems on a clay loam soil. Grass and Forage Science, 68(4), 548-563. Phelan, P., Casey, I. A., & Humphreys, J. (2014). The effects of simulated summer‐to‐winter grazing management on herbage production in a grass–clover sward. Grass and Forage Science, 69(2), 251-265. Yan, M. J., Humphreys, J., & Holden, N. M. (2013). The carbon footprint of pasture-based milk production: Can white clover make a difference? Journal of dairy science, 96: 857-865.

Contacts Dr. James Humphreys, AGRIC, Teagasc, Moorepark, Fermoy, Co. Cork, Ireland. [email protected] Dr. Paul Phelan, AGRIC, Grange, Dunsany, Co. Meath, Ireland. [email protected]