Moving from a pastoral farming system that is more sustainable, in terms of sward diversity, will not be a straightforward process, scientists have warned.
Today most Irish swards comprise perennial ryegrass varieties.
According to Dr. David Patterson, a pastoral and research scientist at the Agri-Food and Biosciences Institute (AFBI), the obvious starting point in this journey to a sustainable farming system is the inclusion of red and white clover species in grassland swards.
Both legumes will fix significant amounts of nitrogen (N) from the air and in theory, this will reduce the quantities of chemical N fertiliser required by swards.
But there are issues according to Patterson, and one of these is the fact that many clover varieties are not that persistent in a commercial environment.
The other main issue relates to the fact that only 30% of the N fixed by clover is made available to other plant species making up a sward.
Patterson, who addressed the AFBI’s 2022 science outlook conference, said that clover inclusion can act to reduce the carbon footprint of a grass sward and an overall livestock enterprise.
He also highlighted that grassland can have a positive impact on the sustainability of agriculture in a number of ways.
He outlined how the actual levels of animal performance can be achieved in a grazing scenario including the use of grassland as a tool to counter the impact of climate change, the impact of grassland on rural landscapes and using grassland management techniques to improve soil fertility levels.
Climate
Paterson also specifically stressed the need to incorporate greater levels of climate change resistance into the development of new perennial ryegrass varieties.
The AFBI scientist also referenced the results of trial work carried out at Loughgall in Co. Armagh during 2020 and 2021. The work was centered on swards containing a mix of grass, clover, plantain and chicory.
Looking to the future, Paterson said trials will be used to identify ways of improving herb persistence within swards and achieving consistent levels of forage output throughout the growing season.
He believes converting to silvo pasture is the ultimate step that grassland farmers can take in terms of diversifying the composition of their swards.
Patterson said research work carried out by AFBI over a 40-plus year period has confirmed the myriad benefits such an approach can secure in delivering a more sustainable grass based production system.
He said the most obvious of these is a significant extension to the grazing season.
But Patterson also believes that the planting of trees will help to lock-up significant quantities of carbon over many decades.
He detailed how AFBI’s current silvo pastoral development work has a key focus on determining the best ratio of tree numbers to grassland area at a specific site.
To date all the livestock studies involving silvo pasture have been focussed on cattle and sheep, but dairy trials will get underway in 2023.