The economic performance of grassland-based milk production using best practices to lower greenhouse gas and ammonia emissions

Economic sustainability is a primary consideration when contemplating adoption of new farming practices to mitigate climate change. Quantifying the impact of adopting best practices to lower emissions on the profitability of dairy production systems is critical to encouraging rapid adoption at farm level to reach emissions reduction targets. The aim was to evaluate the economic consequences of adoption of best practices to mitigate climate change in a typical compact spring-calving grassland-based system of dairy production in Ireland. Data were collected from compact systems-scale experiments conducted at Solohead Research Farm, Co. Tipperary, Ireland (52°51′N, 08°21′W) between 2011 and 2022. There were three systems that had an average of 27 cows per system per year and an average annual stocking rate of 2.53 cows ha −1 . INT was the control in this study and included average annual fertiliser N input of 265 kg ha −1 , applied as calcium ammonium nitrate (CAN 27.5 % N) and urea (46 % N) and the average annual clover content of grassland dry matter was 110 g kg −1 , and slurry was applied by splash plate. BPN included average annual fertiliser N input of 99 kg ha −1 applied as urea or protected urea, clover content was 230 g kg −1 and slurry was applied by trailing shoe. BPO received minimal (<5 kg ha −1 ) inputs of fertiliser N, clover content was 280 g kg −1 and slurry was applied by trailing shoe. INT encompassed each of 7 experimental years, BPN 7 years and BPO 4 years. Herbage, milk and other production characteristics were measured. Relevant farm activity data was modelled on the basis of a 50 ha farm to compare the economic performance of the three systems. There were no ( P > 0.05) differences in herbage dry matter production per ha and milk production per cow between the three systems. BPO was more ( P < 0.05) profitable than INT, whereas BPN was intermediate. Sensitivity of the systems to changing fertiliser N and milk price showed that BPO was more profitable (P < 0.05) in scenarios with intermediate or high fertiliser N prices. BPO had the potential to maintain or improve profitability with substantially lower greenhouse gas and ammonia emissions than conventional grassland-based dairy production (INT). The adoption of practices to lower greenhouse gas emissions from grassland-based dairy production can maintain or improve farm profitability. These results support wider adoption on farms. • Low emissions grassland-based dairy systems were designed and implemented. • Profitability was evaluated at holistic systems-scale (27 cows per system). • Best practices maintained or improved profitability. • Replacing fertiliser N with biologically fixed N was key to the better outcomes.