Scientists are still working to develop technology and systems but earlier this year AgFirst economist Phil Journeaux and AgResearch scientist Cecile de Klein delivered a paper to New Zealand Agricultural Climate Change Conference saying it is impossible to measure farm level emissions.
The Interim Climate Change Committee and the Government both say farmers should pay for emissions from 2025 but the development of simple, cheap and credible technology to calculate those obligations still seems far off.
There are at least four systems developed or under development.
They range from an online dashboard into which farmers put data to create an emissions profile, to work under way at NIWA that will require farmers to attach canisters around the necks of a sample of their stock to capture actual emissions.
Tweaking data required by Overseer nutrient budgets can also be used to estimate farm gas emissions.
Journeaux and de Klein said to verify management changes that lower emissions farmers will need to provide evidence such as invoices, receipts and records similar to those required by regional councils for managing nitrogen.
They say emissions reductions of 5% to 10% are possible through management changes and farm environment plans should include managing greenhouse gas emissions.
Their paper reveals trials have consistently calculated 21.6g of methane is emitted per kilogram of drymatter consumed while nitrous oxide emissions can be calculated based on nitrogen applied.
NIWA chief climate, atmosphere and hazards scientist Andrew Tait agrees the time frame to develop accurate and usable methodology is tight.
His research involves attaching canisters to a sample of animals to accurately measure methane emissions. That data is then scaled over the herd or flock.
Tait says such a system would reward farmers who reduce emissions and penalise those who do not but the challenge is to scale up the technology to make it workable for individual farmers.
“We need to have the ability to detect the impact farmers make with their management of animals, pasture, crops and irrigation so we can see if those decisions are making a difference.”
Tait says NIWA and AgResearch are also developing masts or towers with instruments to record methane, nitrous oxide and carbon dioxide levels.
They are unlikely to be installed on every farm but will act as regional reference points to collect localised information to monitor long-term gas emissions trends.
Similarly, satellite images can be used to monitor gases in the atmosphere.
“There are a number of different ways to tackle these problems but nobody has been able to put it all together,” Tait says.
NZ Agricultural Greenhouse Research Consortium principal investigator Peter Janssen told the conference research is focused on low-methane feed, animal genetics, vaccines and inhibitors.
The largest driver of methane is the amount of feed eaten and research has found grain reduces methane while high forage rape has 25% to 35% less methane than pasture for the same animal performance.
Fodder beet reduces methane by up to 40% when fed at 70% of an animal’s diet.
Genetic traits for low methane in sheep are heritable and those with that characteristic have about 6% less methane yield than the industry average.
Sheep with the trait will be dispersed to a pilot group of ram breeders later this year.
Heritable differences are also expected in cattle and a NZ dairy genetics collaborative working group has been established with the first round of bull testing expected next year.
Janssen says inhibitors show promise in NZ pasture trials, reducing methane production by 20% to 30% in sheep and cattle.
Getting the technology on to farms will take seven years.
