Project Update
Farm to Fork Dairy Systems: transitioning to low N dairy systems on a wetland soil type in the Border Western Region of Ireland
In Ireland, perennial ryegrass (PRG) is the most important pasture species, accounting for 95% of all forage grass seed sales. A key advantage of PRG swards is their suitability to intensive rotational grazing to provide high-quality feedstuff and high stable responses to applied chemical nitrogen (N) inputs. The environmental impact of such systems is questioned and there is increasing interest in the use of legumes to reduce chemical N inputs. White clover (WC) grows well with PRG under temperate Irish conditions and enhances the quality of the sward and the diet of grazing cattle. In addition to sward and animal benefits, Teagasc’s Marginal Abatement Cost Curve analysis has identified the incorporation of WC into grazed pastures as a significant greenhouse gas (GHG) mitigation measure. Despite many positives, WC abundance on grazing farms in Ireland remains stubbornly low and there is a paucity of information on the transition from PRG only to PRG WC swards in particular on colder or more impermeable soil types. The objective of this study is to evaluate the efficacy of transitioning dairy grazing systems from PRG only to PRG WC on impermeable soil types in the Border Western region of Ireland over a 5 year period.
Overall Project Objectives
- To document the evolution in sward WC content within reseeded and over sown PRG swards within an intensive dairy production system on an impermeable soil type
- To quantify the impact of WC content on dairy system performance in terms of grazing season length, supplementary feed requirements and animal performance
- To develop improve grazing management recommendations for intensive grazing dairy farms to transition from high chemical N application PRG systems to lower N PRG WC based systems on wetland soils.
Methodology
Improved efficiency in dairy systems is a significant challenge for the future. As the pressure intensifies to reduce nitrogen (N) losses to the environment from pasture-based dairy systems, interest in PRG WC mixtures, where more N for pasture growth is supplied by biological N fixation (BNF), has been revived. Among the main opportunities to simultaneously improve productivity and sustainability of grazing systems, the incorporation of legumes in grazing pastures to reduce reliance on chemical N application is of critical immediate importance. Equally, while there are numerous studies which show the benefits of WC in swards from an animal performance perspective, the evaluation of various transition strategies for intensive dairy systems from PRG only to PRG WC swards is an area which has received little attention and a major concern for commercial farms. Presently, there is little or no WC present on intensive commercial dairy farms. This study will be the first to document the impacts of transitioning from PRG only to PRG WC swards based on reseeding and oversowing in terms of pasture productivity and botanical composition, animal performance and farm system profitability.
