Best practices to lower GHG and ammonia emissions ‘no threat’ to dairy profitability

Research conducted at Solohead Research Farm has evaluated the impact of adopting key technologies to lower greenhouse gas (GHG) and ammonia emissions on the economic performance of grassland-based dairy production systems.

The results of this study, conducted by Owen Cashman, Dr. Imelda Casey, and Dr. James Humphreys as part of a Department of Agriculture-funded collaborative project between Teagasc and the South East Technological University (SETU), were recently published in Agricultural Systems.

Providing a background to the farm systems study, Owen Cashman explained: “Evaluating the economic consequences of adopting best practices to mitigate climate change in a typical compact spring-calving grass-based dairy system was the key aim of this research.

“We know that economic sustainability is a primary consideration when farmers are thinking about adopting new farming practices to mitigate climate change. Through our research, we wanted to measure the impact of adopting best practices to lower emissions on the profitability of dairy production systems – a key element in encouraging the rapid adoption at farm level to reach emissions reductions targets.”

The study

As part of this study, low emissions grass-based dairy systems were designed and implemented, with three farm systems followed; a control group, a group adopting best practices including artificial nitrogen (BPN), and a group adopting best practices with minimal artificial nitrogen (BPO).

The control group was designed to reflect conventional dairy farming practices, with annual fertiliser nitrogen (N) input averaging 265kg/ha, being applied in the form of CAN and urea, slurry applied using a splash plate and sward clover content was 11%. Data for seven experimental years were available for this system.

Average annual fertiliser N input for the BPN was 99kg/ha, applied as urea or protected urea, whereas slurry was applied via a trailing shoe and sward clover contents averaged 23%. Data for seven experimental years were available for this system.

Sward clover content was higher in BPO system, averaging 28%, whereas artificial N input was kept to a minimum (<5kg/ha of N) and slurry was applied using a trailing shoe. Data for four experimental years were available for this system. Cows in BPO also had a higher EBI to reflect the potential changes in the national herd in future years.

For these three systems, herbage, milk and other production characteristics were measured, while profitability was assessed for each system using a whole-system approach modelled on the basis of a 50 hectare farm.

Results

Some of the key findings from this research are that there were no differences in the herbage dry matter production on a per hectare basis and milk production per cow basis between the three systems ran at Solohead Research Farm. In terms of profitability, the BPO system was more profitable than the control, whereas the BPN system was intermediate of both.

Commenting on the results, Cashman said: “Our research has shown that best practices maintained or improved profitability of grass-based dairy farming systems. Key to this is the role clover plays in replacing artificial fertiliser nitrogen with biologically fixed nitrogen. The BPO system had the potential to maintain or improve profitability with substantially lower greenhouse gas and ammonia emissions than conventional grassland-based dairy production.”

Owen also noted that the changes as examined as part of this experiment – namely the inclusion of clover in grassland swards, switching to protected urea products and the move to trailing shoe technology – “do not necessarily pose a threat to the profitability of grassland-based dairy farms”.

“When compared to the control, both of our experimental systems supported the same stocking rate and milk output per hectare. Relatively high milk sales combined with lower artificial nitrogen costs underpinned the economic competitiveness of the clover-based systems.

“These grass-based systems implementing best practices, and BPO in particular, offer the prospect of substantially lowering GHG and ammonia emissions, while maintaining or improving profitability. Replicating this outcome on commercial demonstration farms will facilitate wider adoption,” he concluded.

For more information on the above study, the full paper is available to access here.

Also read: Solohead aims to develop low emissions blueprint for fragmented dairy farms