Reseeding grasslands does not lead to a loss in soil carbon stocks, according to recent research from Dario Fornara, a soil scientist with AFBI in Northern Ireland and one of the leading researchers on soil carbon sequestration on the island of Ireland.

Many environmental commentators assume that by ploughing land for reseeding or opening the soil, farmers are releasing C02 into the atmosphere. However, the research conducted by Fornara and the team at AFBI shows otherwise.

“The prediction is that if you plough land you will lose soil carbon. The expectation is that there is lower stocks of soil carbon in frequently reseeded grasslands. But this is not what we’ve been finding in our research,” says Fornara.

“We looked at 130 grassland plots and found that if farmers plough and reseed every five years it can rejuvenate the sward without impacting soil carbon stocks. In essence, reseeded grasslands retain as much carbon stocks as permanent pasture,” he added.

Climate

Fornara says the reasons for this are Ireland’s cool, temperate and wet climate, as well as the amount of nutrients that Irish farmers typically apply to their soil – be that as slurry or chemical fertiliser.

“You do see fluxes in soil carbon levels after ploughing for the first few weeks. But that’s not enough to deplete carbon stocks in Irish soils. It’s true that if you plough the soil you lose carbon in the short term but in the long term soil carbon stocks remain the same because the new grass sward will quickly start to sequester C02 back into the soil,” says Fornara.

“Soil carbon stocks will also recover because Irish farmers apply a lot of nutrients to the soil. Nitrogen locks carbon into the soil so you can’t have carbon sequestration without applying nitrogen,” he adds.

Fornara says Irish soils are very resilient when it comes to their stocks of soil carbon and that farmers would really have to mismanage the land in order for carbon to be lost from the soil.

“Because of the climatic conditions here in Ireland and the rate of fertilisation on most farms, I would describe Irish soils as quite resilient. You would really need to mismanage your land to deplete the soils high carbon stocks,” says Fornara.