Dr. Frank O'Mara:

I thank the joint committee for the opportunity to present in relation to sequestration and land management-nature restoration. The Climate Action and Low Carbon Development (Amendment) Act 2021 sets out in law Ireland’s commitment to reducing overall greenhouse gas, GHG, emissions by 51% by 2030 and achieving climate neutrality by 2050. The sectoral emissions targets set by Government in 2022 include a 25% reduction, equivalent to 5.75 Mt CO2 eq., in emissions from the agriculture sector. The setting of a national target for land use, land use change and forestry, LULUCF, has been deferred to allow new scientific knowledge to emerge, but it is expected to be within the 37% to 58% range set out in the 2021 climate action plan. The Teagasc marginal abatement cost curve incorporates measures to reduce emissions or increase sequestration or offsetting from agriculture, LULUCF and bio-energy. The Government has also declared a biodiversity emergency and this, together with the climate targets, has significant implications for land use and management in Ireland. Teagasc is an active member and contributor to the national land use review.

Regarding current land-based emissions, removals and uncertainties, there are large scientific uncertainties associated with the measurement of agriculture and LULUCF emissions and removals due to the biogenic nature of the emissions, making it difficult to mitigate emissions, enhance removals and verify the extent of the mitigation achieved, with this point also emphasised in the climate action plan. These uncertainties can have significant effects on our inventory. For instance, new scientific findings have led to recent changes in the LULUCF inventory which have increased emissions from Sitka spruce on peat soils, which represent approximately 38% of the forest land category. The Environmental Protection Agency's, EPA, latest estimates published in June 2022 indicate that with existing measures, Ireland’s LULUCF emissions will reach 11.1 Mt CO2 eq. by 2030. This represents a 62% increase from 6.8 Mt CO2 eq. in 2018, the base year for our climate plan. If we look at previous projections made as recently as 2021, that indicated a 48% increase from 4.8 Mt CO2 eq. to 7.1 Mt CO2 eq. over this period. One can see the way the figures in the inventory and in our projections are shifting as new scientific information emerges.

These increasing emissions are driven by emission factor refinement for forestry on peat soils; a reduction in the forest sink; sustained emissions from grassland on peat soils; low afforestation rates; and the age-class profile of forests, with a large proportion ready for clear-felling. This highlights the effects that high uncertainties can have on the inventory and the need to have national emission factors to best represent the greenhouse gas emissions from Irish soils. The Teagasc forestry development department is actively promoting targeted forestry as an economically-viable diversification option for farmers. The new forestry programme will provide significantly increased financial incentives and payments for farmers to establish forestry on their land and Teagasc will be working to ensure that this new scheme is widely promoted to farmers.

Turning to grassland emissions and removals, in the Irish inventory, contrary to popular expectations, the largest LULUCF emissions source is grassland, which emitted 7.6 Mt CO2 eq. in 2021. The 3.9 million ha of grassland on mineral soils were estimated in the national inventory to sequester 2 Mt CO2 eq. However, there was approximately 337,000 ha of managed pasture on drained peat soils, which were calculated to emit 9.6 Mt CO2 eq. The high emissions from drained peat more than negate the carbon removals on mineral soils that cover an area tenfold larger than peat soils.

As stated, there is high uncertainty relating to emissions and removals surrounding LULUCF. New emission factors emerging from scientific research can have a large impact on inventories. Currently, the emission and removal calculations for grassland in the national inventory use generic tier 1 emission factors and there is an urgent need to generate national-specific factors for grassland on mineral and organic soils.

Teagasc is currently establishing the national agricultural soil carbon observatory, NASCO, which will be completed in 2023. This observatory will consist of circa 30 sites where field-scale CO2, CH4, or methane, and water fluxes will be directly measured using eddy covariance flux towers. Of the 30 towers eight are being established on agricultural grassland on peat soils and 22 on mineral and peaty mineral soils. The current extent of grassland on peat soils is also uncertain, with current estimates of between 300,000 to 400,000 ha. Research is being carried out to better quantify this area. Further research is also required on the drainage status of these agricultural peat soils, as drainage was carried out in the 1960s and 1970s with little knowledge on maintenance and status of drains since installation. The drainage technology used at the time was not as efficient as modern drainage practices. Both of these factors result in high uncertainties about the drainage status of these grassland peat soils.

Teagasc has commenced a number of research projects on agricultural grasslands on peat soils and recently appointed a new permanent researcher to deepen the organisation’s capacity in this area. A new research project, ReWet, has commenced, which is testing management strategies for rewetting drained grasslands on peat soils. This research will provide practical demonstration for farmers on how to rewet soils and evaluate the efficacy of different practices. Teagasc is also part of an international European joint programme, EJP, Soil project called INSURE, which is developing indicators for successful carbon sequestration and greenhouse gas mitigation by rewetting cultivated peat soils with partners in Finland, Norway, the Netherlands and Switzerland. Teagasc research will build on the NASCO investment and the peat farming European Innovation Partnership, EIPs, funded by the Department of Agriculture, Food and the Marine in 2021. Within the Teagasc signpost farms programme, the soil organic carbon baseline levels are currently being measured across approximately 120 signpost farms, with these soils being re-sampled regularly.

Regarding mitigation measures and enhancing carbon sinks up to 2030, there is considerable scope to both reduce LULUCF emissions and to enhance carbon sinks. In order to achieve long-term net climate neutrality, the rate of afforestation will have to increase significantly. Increasing afforestation rates to 8,000 ha per annum by 2030 would result in a 2.1 Mt CO2 eq. sequestration by 2050.

However, in the short term afforestation will contribute little to 2030 targets due to the fact there are net GHG emissions are associated with land preparation for forest establishment and forestry takes a period of time to achieve maximum growth rates. Alternative management of the current forest estate provides an opportunity to maintain the forest carbon sink. Reduction in deforestation and extending forest rotations could reduce and delay emissions associated with harvest, although impacts on forest owners’ incomes and the timber industry would need to be carefully assessed.

Reducing the large emission source associated with managed grassland on peat soils will be imperative for LULUCF mitigation as it is the largest source. Reducing CO₂emissions from grassland on peat soils generally involves raising the water table but not flooding. In addition, the input of nutrients from animals, manures and mineral fertilisers further increases CO₂emissions. Experiments investigating alternative management strategies for grassland on peat soils, ranging from reducing nutrient input to raising the water table by different amounts, have commenced in Teagasc. The impact on farmers’ incomes and catchment spillover impacts much be carefully assessed.

The impact of grassland management on mineral soils is also being explored as part of the VistaMilk Science Foundation Ireland, SFI, Research Centre where we are using a combination of flux towers, soil carbon measurement and soil carbon modelling to quantify the impact of management, such as soil fertility, multi-species swards and grazing intensity on soil carbon sequestration. Modelling conducted as part of the Teagasc marginal abatement cost curve, MACC, suggests that improved pasture management on 450,000 ha of mineral soils can sequester an average of 0.26 Mt CO₂per year by 2030. This data will be used in conjunction with earth observation data from satellites and drones in order to estimate plant growth which in turn is being used to model CO₂balance for forest, crop-land and grassland ecosystems across the country as part of a Microsoft-SFI co-funded data platform called Terrain AI - artificial intelligence - led by Maynooth University and involving Teagasc, Trinity College Dublin, TCD, University College Dublin, UCD, Dublin City University, DCU, and University of Limerick, UL.

The carbon sequestration potential of hedgerows has been investigated in Teagasc for many years, for example as published by Green et al. in 2019. Teagasc research has recently been completed to improve the capacity for national estimation of hedgerow carbon sequestration in an Environmental Protection Agency, EPA, funded farm carbon project in conjunction with Forest, Environmental Research and Services, FERS, Limited. This research found that increasing hedge width and height can substantially increase both above and below-ground carbon sequestration while supporting biodiversity but that removal of hedgerows and replacement with young hedges results in carbon loss. The project estimated that nationally the mean carbon stocks across all hedgerows were 67 tonnes of carbon per hectare comprising 57 tonnes of biomass above ground and 10 tonnes of biomass below ground. Improved crop-land management via straw incorporation, use of cover crops and targeted incorporation of manures and-or digestate can also contribute significantly to improved carbon balance while improving soil health and nutrient availability and reducing nitrate leaching to water. Research has recently started in developing agro-forestry for cattle to increase carbon capture by trees and mitigate emissions from cattle.

The next decade and beyond provides the agriculture and land-use sectors with challenges, but also opportunities. Research currently under way by Teagasc and others will reduce the uncertainty associated with land emissions and sequestration, which is particularly important for managed grasslands on peat soils. Improved management of mineral soils can enhance carbon sinks and improve nutrient availability, reducing the need for and cost of fertiliser inputs. Forestry will have a very important role to play in the journey to climate neutrality, and the incorporation of trees into agricultural systems, via shelterbelts and-or agro-forestry could also improve carbon sequestration. New ways of utilising our soils and our landscape and tailoring land-use solutions for specific situations will be required.