Many of Ireland’s hedgerows aren’t actually sequestering carbon, Teagasc researcher Professor Gary Lanigan has said.

“The bad news is when we did a survey around Wexford and Waterford, hedgerows were a source [of carbon] because there are less hedgerows now than there were previously.

“So, when people ask me how much carbon [their hedgerow] is sequestering, the answer is actually less than zero,” he said.

Prof Lanigan was speaking at the Agricultural Science Association (ASA) ‘Carbon Cycling, Measurement, Accounting and Policy’ symposium at Johnstown Castle, Co Wexford on Wednesday 8 March.

However, in what he described as “good news”, Teagasc researchers have found that emerging or new hedgerows are locking in carbon on farms.

“When we did the farm carbon project, what we found was that our hedgerows, emerging hedgerows, so new hedgerows, lock up a substantial amount of carbon, about 3.7t of carbon [per hectare],” he said.

Prof Lanigan explained that as a hedge moves from being “very well managed” and regularly cut to being more “unmanaged”, it gains a lot of carbon.

“Moving from a managed to an irregularly managed hedgerow, you gain about just under 3t of carbon per hectare to anywhere from 1-3t of carbon per hectare, depending on the profile of that hedge,” he told farmers at the event.