Agricultural emissions lower than thought, new data reveals

Beef cattle emissions are 5 percent lower, and sheep emissions more than 1- percent lower.
Beef cattle emissions are 5 percent lower, and sheep emissions more than 1- percent lower. Photo credit: Supplied/Beef and LambNZ

By Andrew McRae of RNZ

Enhanced data on greenhouse gas-emissions from livestock shows agriculture is contributing fewer emissions than first thought.

Research conducted by AgResearch has expanded on the data gathered, has a more comprehensive breakdown on livestock types and pastoral conditions across the country and now includes the high country.

AgResearch senior scientist Tony Van der Weerden said data on nitrous-oxide emissions from 10 years of additional field trials is now more accurate, particularly as it separates sheep and cattle.

Total emissions in New Zealand from sheep are 10.6 percent lower than they were under the current emission factors, beef cattle emissions 5 percent lower and dairy cattle emissions 1.4 percent lower.

''Across the whole agriculture scene we are going to see a (total) reduction of 4.4 percent in nitrous oxide emissions from the agricultural sector,'' Van der Weerden said.

It could be seen as welcome news for the farming sector which often gets the blame for greenhouse gas emissions.

''It's important to note that it isn't any mitigation strategy, as it is really a more accurate accounting of the emissions coming from the agricultural sector," Van der Weerden said.

''It is good news in terms of ensuring we are getting a more accurate assessment of what those emissions are (but) at the same time agriculture is still the largest contributing sector,'' he said.

Trials on different terrain showed lower emission factors on steeper, sloping land.

He said it has an impact for sheep, beef and deer farming.

''We have calculated emission factors that are appropriate for different topographies and then analysed the data and group the data according to significant differences.'

''At the end of the day we have two topography classes - flat land and low-sloping land - with one set of emission factors for urine, and then for medium and steep-sloping land another set of urine emission factors.''

Van der Weerden said there were implications for New Zealand achieving net-zero nitrous oxide emissions by 2050.

''It suggests the actual amount that needed will be a little bit lower for sheep and beef farmers than it was previously.'

''There are implications there but that's a policy-type decision that needs to be made further on down the track.''