A new study from Teagasc has found that using diverse grass mixes in dairy farming systems can lead to increased farm profits while cutting nitrogen (N) fertiliser application levels.
The three-year trial compared three different pasture systems: a standard perennial ryegrass sward receiving high levels of chemical N application (250 kg N/ha), a ryegrass-white clover sward mix receiving a medium level of chemical N application (125 kg N/ha), and a more diverse multispecies sward containing grasses, clovers and herbs, also receiving a medium level of chemical N application (125 kg N/ha).
The research measured both the performance of the swards and the dairy cows exclusively grazing those swards over 3 consecutive years (2021-2023). Subsequently, using Teagasc’s economic modelling tools, the costs and profits of running each system on a 40-hectare dairy farm were calculated. The aim of this analysis was to see which system delivered the best economic returns for farmers, under real-life price and weather conditions.
Results showed that the multispecies sward was the most profitable option. It outperformed the high-fertiliser ryegrass system by €167 per hectare and the clover mix by €148 per hectare. This gain came mainly from higher milk output and lower fertiliser costs. Cows on the multispecies swards produced more milk solids per cow with reduced chemical N application, while achieving similar pasture production and quality to the perennial ryegrass only high chemical N application treatment.
The ryegrass-white clover system also produced extra milk output and also reduced N fertiliser costs, but due to lower than anticipated clover contents (17% per annum), it also produced less grass than both other treatments, leading to extra silage being purchased within that system. As a result, its overall profitability ended up similar to the high-fertiliser ryegrass system. The modest benefit of white clover due to the relatively low and variable clover content across the paddocks, highlights the necessity to achieve and maintain a higher contribution of white clover (>20%) over time to maintain pasture productivity across a farm. While multispecies swards require more attention when it comes to establishment and persistency of sown species, the study showed that even with a moderate increase in reseeding frequency, the economic benefit was still maintained.
Commenting on the findings, Alann Jezequel, who undertook his PhD studies on this project, said: “Similar to many recent studies in Ireland and elsewhere, our results show that it is possible to reduce N fertiliser use and still maintain or even improve farm profitability through better use of species-rich pastures. But success depends on good establishment and consistent subsequent grazing management. It’s not a one-size-fits-all solution and farmers will need the right support to make it work on their own farms.”
For farmers facing high fertiliser prices, pressure to reduce emissions, and increasingly unpredictable weather, this study indicates that increasing sward diversity (using both white clover and MSS) can support profitable and sustainable dairy production systems into the future while reducing our reliance on chemical N application. It also flags the need for good establishment and management practices, especially when relying on clover or herbs like plantain and chicory.
These findings mark an important step towards developing dairy systems that meet both environmental goals and farmer bottom lines. Further work is now needed to see how these systems perform over the longer term, particularly in maintaining sward quality and species persistence.
To read more about Climate and Biodiversity research in Teagasc, visit the Teagasc Climate Centre.