Government told to move quicker on carbon sequestration
The best existing ways to increase carbon sequestration on farms are to plant additional woodlands.
Dairy farmers wondering what the government will throw at them next under climate and nitrates regulations should start swotting up on carbon sequestration.
The Government's Climate Action Plan 2023 includes a commitment to impose mandatory carbon sequestration requirements for nitrates derogation farmers, and the first quarter of 2023 was the due date.
The Climate Change Advisory Council (CCAC) has now written to the Government saying the carbon sequestration commitment appears to be delayed or behind schedule, and to get on with it. The CCAC is the independent advisory body assessing and advising on how Ireland can transition to a low-carbon, climate-resilient and environmentally sustainable economy.
The letter from CCAC Chair Marie C Donnelly warned the Government that a downward emissions trajectory in 2023 is crucial, and any delay risks failure for 2030 emissions to stay within agreed carbon budgets. Delays would also lead to higher emissions than anticipated, which would have to be addressed in subsequent plans.
Included among the six most critical actions that the CCAC said to appear to be delayed or behind schedule is imposing mandatory derogation requirements under the Nitrates Regulations to enhance carbon sequestration.
The CCAC also voiced its concern that two major carbon budget elements are outstanding. One of these is the sectoral emissions ceiling for LULUCF (Land Use, Land-use Change and Forestry), another area which directly concerns farmers and landowners.
According to Teagasc, the best existing ways to increase carbon sequestration on farms are to plant additional woodlands or forests and to restore drained wetlands. If 5,000 hectares of agroforestry (growing trees combined with animal or crop agriculture) were established before 2030, it would accrue up to 26,000 tonnes of carbon dioxide equivalent per year sequestration by 2030.
Next best are improving soil fertility, establishing clover or multi-species swards, and planting extra hedgerows. Planting 10,000km of new hedgerows would increase carbon sequestration by about 9,500 of carbon dioxide equivalent per year.
However, national research is urgently required to confirm carbon sequestration (and methane reduction) benefits suggested for multispecies swards. Other ways to increase carbon sequestration are avoiding soil compaction, increasing grazing, and allowing existing hedgerows to be taller and wider.
In the longer term, use of digestate from anaerobic digestion will increase carbon sequestration. Sequestration by forming carbonate minerals in soils can be promoted artificially, for example, by addition of basalt rock dust to soils.
Increased application of pig slurry on cropland will improve low soil organic carbon systems. If 50% of pig slurry is spread on tillage land, this would result in 11,200 tonnes of carbon dioxide equivalent per year abated.
According to Teagasc researchers, mineral grassland soils already contain large stocks of carbon, equivalent to 30 years’ worth of carbon emissions. Unreclaimed peat soils store even more per hectare.
Grasslands are generally a carbon sink (sequestering more carbon than they release). But international accounting rules allow credit only for additional sequestration that occurs due to management changes. In contrast to mineral soil, grasslands on drained organic (peat) soils are a substantial source of carbon emissions.
Restoring (rewetting) small areas of peat soils can deliver large carbon savings. Carbon stored in soils is often called soil organic carbon and it is good for soils, improving their workability, water holding capacity, and productivity.
