'No silver bullet' for greenhouse gas problems in farming sector

Swapping national dairy herd for crops 'could increase emissions'

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Caroline O'Doherty

Switching farms from cows to crops or feeding animals seaweed are not going to provide 'silver bullet' solutions to Ireland's biggest greenhouse gas problem, farming experts have said.

Swapping the national dairy herd - the country's single biggest producer of carbon emissions - for tillage fields could even increase emissions by ploughing up carbon stored in the soil for centuries.

Experts gathering in Dublin to discuss dairy and climate change warned that some of the ideas being put forward as solutions to the sector's emissions were overly simplistic.

Professor Gary Lanigan, a greenhouse gas scientist, said changing the diet of cows to reduce the amount of methane they produce was being studied but the results were mixed.

"The seaweed idea has merit but you need an awful lot of it. You can add nitrates to the diet but there's a danger of killing the animal from nitrogen poison. You can feed them urea but that creates ammonia which causes a pollution issue," he said.

"There have been programmes, particularly in New Zealand, looking for silver bullets for the past 20 to 30 years and they haven't found any yet."

Agriculture is responsible for a third of Ireland's greenhouse gas emissions, and dairy is by far the biggest contributor. National policy is to increase the dairy herd but environmentalists have called for a halt to this and a possible switch to crop production.

Prof Lanigan said there was no easy answer in that route either as the permanent grasslands which support the dairy sector are natural carbon stores. "If we were to double our tillage area we would release somewhere in the region of 345 tonnes of CO2, which is equivalent to about 100,000 cows," he said.

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Dr Ken Byrne of the School of Natural Sciences in the University of Limerick, said much more forest had to be planted and peatlands restored to serve as carbon stores.

Climate Action Minister Richard Bruton has announced plans to plant 440 million trees by 2040, but Dr Byrne said it was of concern that repeated Government targets for increasing tree cover have not been achieved.

He said farmers showed little appetite for planting trees and often cited the restraints of the Forestry Act which states once land is put in forestry it cannot be changed to other uses.

Irish Independent

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