Can Irish agriculture become carbon neutral i.e.net zero carbon emissions? Europe’s recent “Green Deal” aims to prevent climate change by bringing carbon emissions to zero by 2050, writes Donal O’Brien, Teagasc Research Officer.
Beef and dairy production are the largest Irish agricultural industries and the main cause of the sector’s emissions. Reducing the national herd’s carbon emissions close to zero, while feeding a growing population, will be very challenging.
Currently, the main strategies available to improve the herd’s carbon emissions/unit of output (i.e. carbon footprint) are 1) Improve efficiencies 2) Low emission technology 3) Carbon sequestration.
Generally, a better ratio of output to input reduces carbon footprint and improves economic competitiveness. Decisions widely recognized to cut carbon footprint by improving the output-input ratio include:
- Increase genetic merit;
- Optimize calving rate: 0.95-1 calf/cow;
- Improve 200-day weaned weight/beef cow weight;
- Reduce age at 1st calving to 22-26 months;
- Rotationally graze cattle;
- Spread slurry in spring.
Low emission technologies
Many tools and additives are reported to reduce farm emissions, but few are effective permanently. Technologies recognized to reliably reduce carbon emissions are:
Protected urea: Stabilizing urea with NBPT/NBPT+NPPT/2-NPT moderates the rate nitrogen (N) is converted to nitrate by approximately 1-2 days, which substantially reduces N losses.
Slightly slowing this process has no impact on grass yield. Applying protected urea instead of CAN to grassland reduces carbon emissions from fertilizer by 50% and is better value.
Low emission slurry spreading (LESS): LESS machinery delivers slurry onto soil in narrow bands, which minimizes the surface area exposed to air, resulting in less N loss than a splash plate.
The technique improves growth and displaces chemical N, which reduces carbon footprint. Hiring a contractor to spread slurry with their machinery minimizes the cost of changing to LESS.
Figure 1. Technologies for low emission farming: a) Trailing shoe b) Protected Urea (KaN)
Grassland and hedgerows remove CO2 from the air via photosynthesis and can store it in the soil by a process called sequestration. The soil process may be enhanced by:
Improving grassland productivity: Producing grass efficiently by liming soils to pH 6.3-6.5, and by applying fertilizers according to soil test results, is among the main practices to enhance soil carbon.
Introducing white clover into swards can benefit sequestration too when N fertilizer application is curtailed. Carbon gained by sequestration is easily lost by overstocking and deep ploughing. Both should be avoided.
Planting hedgerows and trees: Preserving hedgerows by trimming to an appropriate height is maintains carbon in hedges. Planting hedgerows in areas unsuited to grassland or adding trees to existing habitats enhances sequestration.
Carbon action plan
Deploying each strategy as part of a carbon action plan can significantly improve the low carbon footprint of Irish beef and dairy (Figure 1).
Based on current growth rates, these potential gains would enable agriculture to meet national commitments for climate action plan 2019 and lay a foundation for achieving 2050 goals.
Promising low emission technologies are starting to emerge, which could mean future Irish milk and beef will have little or no carbon footprint. Low carbon farming is likely to create new income streams and add value to milk and beef products.
Figure 2 Potential effect of improving efficiencies (EFFCY), low emission technologies (TECH) and enhancing carbon sequestration (C SEQ) on average carbon footprints of suckler beef and dairy farms.