Chris Horn: To help reduce emissions on the farm, scientists are looking out to sea

Certain types of seaweed have properties that can curb methane production in cattle, but more research needs to be done

At the end of July, the Government announced a set of ceilings for the maximum limits of greenhouse gas emissions across a range of sectors, to the end of the decade. These include a 25 per cent reduction for the agricultural sector, 35 per cent for general industry, 40 per cent for residential housing, 50 per cent for transport and a full 75 per cent reduction for electricity generation.

From the perspective of the other sectors, agriculture appears to be allocated a modest reduction. Nevertheless, 35 per cent of greenhouse gases in Ireland come from farming, compared to an EU average of just 11 per cent, and more than 60 per cent of our figure comes from methane produced by belching ruminant animals. Furthermore, agricultural emissions actually rose by 4.7 per cent from 2020 to 2021. Substantial adjustments are thus needed. There are predictions that the sector may mutate into a relatively small number of large “ranch-style” farms, with the loss of part-time farming and of smaller farms particularly in the beef suckler sector. Last November, a commissioned report by the Irish Farmers Journal forecast that were the emissions reduction to be a full 30 per cent, then 56,000 of the 265,000 jobs in Irish farming would be lost.

Some 80 per cent of Irish agricultural produce is exported, with a well-deserved emphasis on natural, healthy and fresh products and especially those from grass-feed beef and dairy. Beyond the simple economics, Irish farming has built an aura for environmental care and community participation. Rather than crippling the sector, perhaps the reduction in emissions could be an opportunity to reinforce the intrinsic concern that many farmers have for the preservation and nurture of the environment. The Teagasc Signpost programme, launched in late 2020, already identifies a number of complementary measures to reduce emissions, leading to more sustainable and profitable farming. But is there a single natural and environmentally friendly innovation which could make a dramatic impact on emissions from ruminant animals?

In 2019, a US study conducted over three weeks on dairy cows showed reductions in methane emissions of up to 80 per cent, by adding modest quantities of a warm-water red algae seaweed, Asparagopsis taxiformis. Subsequent studies in New Zealand and Australia of the cold-water equivalent, Asparagopsis armata, have shown that a 1-3 per cent dried seaweed additive can give methane reductions of 60-90 per cent. Not only are these reductions extremely significant, but using a natural, organic suppressant is much more acceptable than any reductions that might be achievable through synthetic chemical feed additives derived from fossil fuels.


So, where’s the catch? In both seaweeds, a chemical called bromoform actively suppresses the ruminant methane release. However, bromoform is a known carcinogen in animals and humans, and also depletes the ozone layer. Although the bromoform is locked away inside macro-cellular structures within the seaweed, researchers are naturally cautious. Furthermore, in the cold waters of the Atlantic and around our own coasts in particular, Asparagopsis is rare and certainly not economically available to farm for large-scale use for our ruminant animals.

Since early 2020 in the EU-funded SeaSolutions project, Teagasc has been screening those seaweeds abundant in Irish and Atlantic coastal waters to identify varieties that could substantially reduce emissions. Dr Maria Hayes at the Teagasc Ashtown food research centre is the principal officer, leading a collaboration of Canadian, German, Irish, Northern Irish, Norwegian and Swedish researchers. The project is funded until next year. Discussing her work, she explained to me that two seaweed extracts have been identified so far, which show meaningful potential.

In trials, animals find them palatable; their health has improved and they have gained weight. The seaweeds can be either directly harvested or cultivated, and the processing costs to produce the feed additive are realistic. The methane reductions so far have been in the order of 10-20 per cent, which although substantially less than those reductions claimed for Asparagopsis, are still sufficiently significant to make an impact. Potential side effects from the extracts are being carefully monitored, in particular the iodine levels in the extracts, which are below levels stipulated by the EU.

Not unexpectedly, there is considerable commercial interest in the work from feed suppliers and others, both within the EU and elsewhere. Trials in both beef and dairy cattle, and in sheep herds, are continuing in Ireland and with the international partners.

The end of the decade is but seven years away. Technological innovation and change in the agricultural sector have not always been precipitative, but there is an increasing recognition by both the general public and policymakers that society needs rapid action to materially impact greenhouse gas emissions. In the case of agriculture, whilst the scale of the reductions imposed relative to other sectors may appear modest, there is nevertheless the possibility of substantial disruption and change in income. It would seem that while there is no single “silver bullet”, organic seaweed could play a critical role. Natural organic solutions taken to reduce emissions would certainly amplify Ireland’s position as a high-quality and healthy food producer.