New Zealand's Greenhouse Gas Inventory is the official annual estimate of all human-generated greenhouse gas emissions. The most recent inventory for the period from 1990 to 2018 incorporates new research on livestock emissions on different land gradients.
AgResearch and Manaaki Whenua scientists have carried out research for over a decade on livestock emissions. Scientists found that on rolling and steep hill country land, nitrous oxide emissions from urine is lower, as a result of factors related to soil composition and topography. Emissions for dairy cattle on flat land were also recalculated to be slightly lower as a result of their research.
While the impact of the changes for 2017 is modest – with total dairy cattle emissions being 1.4 percent lower than previously estimated for that year, DairyNZ strategy and investment leader Dr David Burger says the research is important.
“We now have more accurate estimations of livestock emissions on sloping land,” says Dr Burger.
“The current inventory calculations assume almost all dairy cattle are located on flat land, but we know that cows are often grazed on rolling land, particularly when they are young or during winter.
“Once we have more data on the proportion of dairy cattle on sloping pastures, we will have a more accurate understanding of emissions which may see dairy nitrous oxide emissions change further.
“As part of the Dairy Tomorrow strategy, dairy farmers have committed to protecting and nurturing the environment for future generations,” adds Dr Burger.
This commitment includes work to lead efforts to meet New Zealand’s climate change goals through identifying and implementing strategies to reduce or offset greenhouse gas emissions on dairy farms.
Under a 2019 partnership agreement (He waka eke noa) between the government and primary sector organisations, all farmers will work to have Farm Environment Plans by 2025 which set out how good farming practices will help to manage emissions.
Since 2017, the number of milking dairy cows in New Zealand has remained relatively stable (at 4.85 million in 2016/17 and 4.95 million in 2018/19).
For more information on the AgResearch and Manaaki Whenua research visit agresearch.co.nz/news.
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