F2FSystems: the evaluation of Low-Nitrogen pasture-based regenerative grazing systems
As part of the management of intensive grazing, the focus on simple and productive forage systems has led to a limited range of plants being used in grazing swards and supported by higher levels of chemical fertilisers and supplemental feeds. With increasing pressures on all agricultural systems to reduce environmental impacts while increasing productivity, there is a growing awareness of the potential of additional forage species to improve the performance of grazing systems. Recent studies suggest that the yield and quality of multi-species swards containing perennial ryegrass (PRG), white clover (WC), alternative legumes such as red clover and forage herbs such as chicory and plantain are comparable with PRG only and PRG-WC only grazing swards, with lower fertiliser N inputs required. To date however, there is limited data on the performance of intensively managed diverse pastures under grazing and there has been relatively low adoption of more diverse mixtures. The objective of this cross-disciplinary project is to evaluate the potential of PRG WC and MSS swards to support high productivity with a reduced requirement for chemical N application in pursuance of more environmentally friendly regenerative grazing systems for Ireland.
Overall Project Objectives
The objective of this experiment is to compare the performances of perennial ryegrass only, perennial ryegrass white clover and diverse multispecies swards under intensive grazing at multiple sites within intensive multi-year pasture-based grazing systems in terms of
- herbage DM production, sward botanical composition and nutritive value
- animal performance, animal health and welfare
- nutrient efficiency and conservation
- product quality and character
- Furthermore, the further development of multispecies grasslands, improved modeling on nutrient movements and a qualitative evaluation of farmer attitudes to legume based swards will also be evaluated as specific studies within this overall project.
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 and Teagasc is tasked with the development of such systems in Ireland as part of the National Climate Action Plan. Recent studies suggest that the DM yield from multispecies swards containing perennial ryegrass (PRG; Lolium perenne L.), white clover (WC; Trifolium repens L.), and herb species are comparable with PRG and PRG-WC grazing swards, with lower fertiliser N inputs required (Finn et al., 2013; Grace et al., 2018). The structure of the farm systems experiment component of this project will be to compare the animal and pasture performances of 3 grazing systems based on various pasture types (a monoculture of PRG, a PRG WC sward and a multispecies pasture incorporating 40% PRG, 15% other grasses, 30% legumes and 15% herbs) at 2 sites. Detailed animal (milk production, milk composition, bodyweight and BCS and DM intake) and pasture (yield, quality, utilisation efficiency and botanical composition) data will be collected at Johnstown Castle and Moorepark sites to quantify the impacts of sward and animal type on intensive farm system performance.