Stocking rates of 2.5 cows/ha can be easily sustained without having to spread any fertiliser, principal research officer at Teagasc’s Solohead farm Dr James Humphreys has said.

Carrying a stocking rate of 2.39 cows/ha at Solohead without spreading any nitrogen fertiliser, Humpheys said, is not a challenge due to the type of clover swards sown on the Tipperary-based farm.

“The derogation is really under question and I think that’s a pity because we can easily carry a stocking rate of 2.39 cows/ha with no nitrogen fertiliser. If we had to cut the stocking rates further than that, say if we had to go less that two cows per hectare – the question is, what would we do with the additional grass?

“You’ve two options – if you were forced to cut stocking rates any further you either cut cow numbers on the farm or you increase the farm area by taking on more land,” he told a recent Teagasc Signpost webinar.

This, Humphreys argued, raises the question if this is the best way to use our land resources. He suggested that land sparing options should be considered such as carbon offsets and biodiversity.

“We have a system that can work very well at about 2.4 cows/ha or 2.5 cows/ha with no nitrogen fertiliser, cutting it makes it less efficient,” he said.

Fertiliser reductions can often be easier done on beef farms than dairy farms, Humphreys maintained.

He also highlighted how beef farms can be part of the collective effort to reduce emissions.

Humphreys discussed the LoCAM-dairy (lowering the carbon and ammonia footprints of pasture-based dairy production) project which is taking place at Solohead currently.

No surprise

“It’s no surprise that around 57% of nitrogen fertiliser is used on dairy farms, but there’s still a substantial proportion (33%) of nitrogen fertiliser used on beef farms.

“You could argue that reducing fertiliser on these beef farms is a much easier step to take than it is on dairy farms.

“The point I’m trying to make is that if we are going to use fertiliser to cut emissions, it can’t just be on dairy farms – it needs to be across the board and I think there are economic benefits to go along with that,” he said.

In terms of reducing greenhouse gas (GHG) emissions, cutting nitrogen fertiliser usage on farm is the low hanging fruit, he maintained.

“If we were to work towards zero nitrogen fertiliser use on grassland farms in Ireland... we’ve seen in Solohead that we can maintain and get higher profitability. It would lower national GHG emissions by 10% and ammonia emissions by 24%.

“We would achieve the same level of national output and export value and it would have a positive impact on balance of payments,” he said.