Reducing agricultural greenhouse gas emissions is challenging but achievable

The agriculture sector has embarked on a journey towards reducing greenhouse gas emissions, mainly methane and nitrous oxide. It will be one of the most important but challenging journeys, the sector will ever have to make.

Farmers are being encouraged to implement a range of measures which have been identified by Teagasc. This initiative to implement mitigating technologies is being led by the Teagasc Signpost programme, a partnership between Teagasc and over 50 public and private organisations and companies, and over 100 Signpost demonstration farmers all committed to taking climate action by reducing emissions on their farms.

“The reduction targets set for the agriculture sector are certainly challenging, but in the right circumstances, they could be achievable,” says Teagasc director Frank O’Mara. “It will require the widespread implementation of the suite of mitigation measures identified in the Teagasc marginal abatement cost curve (MACC), a stable bovine herd, some change in land use and a new suite of future technologies that are currently in early-stage research.”

Unlike other sectors of the economy, agriculture generates just a small amount of greenhouse gases in the form of carbon dioxide. Methane and nitrous oxide are the main greenhouse gases produced by agricultural activity. The initial focus is on emissions from synthetic nitrogen fertiliser usage and animal manures, key sources of nitrous oxide emissions. By contrast, methane, mainly generated by the digestion process in bovines, is hard to mitigate with currently available technologies.

“Teagasc would like to see clover and mixed species incorporated into all grass reseeds by farmers in 2022,” says O’Mara. “These actions will naturally add nitrogen to the soil, opening up the possibility of reducing the quantity of synthetic nitrogen applied to the land by farmers.”

Fertiliser type

A big switch in fertiliser type, from calcium ammonium nitrate (CAN) to using protected urea is also recommended, with a target of changing 65 per cent of CAN to protected urea by 2030. An increase in the quantities of lime used on farms to 2 million tonnes annually by 2030, will ensure greater availability of the nutrients in the soil for the growing plant, further limiting the impact on grass yields of any reduction in synthetic fertilisers.

“How farmers manage farmyard manure and slurry on farms is also changing,” O’Mara adds. “Many have switched to using low emissions slurry spreading equipment, reducing emissions and improving fertiliser value.”

Ambitious targets to continue this technology adoption have been set with a target of 60 per cent of all slurry spread by low emissions slurry spreading equipment by 2022; 80 per cent by 2025; and 90 per cent by 2027.

“Improving the health of animals in the national herd, will improve performance and the efficiency of production, thus improving the lifetime carbon footprint of those animals,” O’Mara explains.

Animal breeding is a well-proven strategy to deliver healthier and more productive animals and has been proven to deliver efficiencies both in the use of feed and nitrogen use, as well as in carbon emissions. The Irish dairy cow today is 14 per cent more carbon efficient following 20 years of breeding gains.

“The rate of gain can be accelerated through a combination of more accurately identifying the genetically elite animals and explicitly including measures of carbon and nitrogen efficiency in the breeding indexes,” says O’Mara.

DNA screening

Rapid progress in DNA screening is contributing to the more accurate identification of genetically elite animals. “Ireland was the second country in the world to release DNA-based evaluations of dairy cows and our beef DNA-based evaluations are the envy of the world, with the Irish Cattle Breeding Federation and Teagasc collaborating to ensure early availability of these advances to Irish farmers” O’Mara adds.

DNA-based genetic evaluations were recently provided to Irish sheep farmers. These evaluations can increase the rate of genetic gain by at least 50 per cent.

Ireland is also investing heavily in the large-scale measurement of methane emissions from individual dairy and beef cattle as well as sheep. The goal is to identify low-emitting animals who, themselves will become parents of the next generation, thus cumulatively reducing the quantity of methane emitted as a whole.

The Meth-abate research project is looking at developing novel farm ready technologies to reduce methane emissions from pasture based Irish agricultural systems. It is investigating feed additives to mitigate methane emissions while monitoring their effects on animal productivity.

A raft of other technologies have the potential to play a role in reducing emissions, such as earlier finishing of beef cattle, changing compound fertiliser formulation and anaerobic digestion among others. And in terms of carbon sequestration, soils, trees and hedges are all making a contribution which can be enhanced.

“A concerted effort by farmers, researchers, advisors, and educators, along with those working in the agri sector, will be required to implement the technologies identified and in the research pipeline,” says O’Mara. “These small individual steps, when combined, will be required over the next decade to get from the 2018 reference level down to the target set by 2030.”