NZ Livestock Responsible For Less Emissions Than Previously Thought

A recent finding that livestock are responsible for less nitrous oxide than previously estimated underlines the value of in-depth research and accurate data.

Federated Farmers of New Zealand thanks the researchers at AgResearch and Landcare Research and the officials at MPI who continue to work hard to improve the accuracy of New Zealand’s national greenhouse gas inventory, Feds climate change spokesperson Andrew Hoggard says.

Nitrous oxide (N2O) is a greenhouse gas that is both long-lived and potent. Federated Farmers supported the 2050 net-zero N2O target that was recently added to the Climate Change Response Act. This will require our livestock industry by 2050 to either reduce or offset the about 8.700 kilotonnes of CO2- e (carbon dioxide equivalent ) of nitrous oxide that were emitted in 2017 (the most recent year data is available for).

"Achieving net-zero nitrous oxide emissions by 2050 will not be easy to do, but is nonetheless a task we are committed to," Hoggard says.

"The difficulty in reducing nitrous oxide is due to the emissions being mainly caused by the urine of livestock providing too much nitrogen for the soil to absorb. While nitrogen is good for plant growth, when there is too much nitrogen in one spot, some will be released into the air as nitrous oxide."

The absurd impracticality of measuring the emissions caused by the urine of individual livestock on farm means that totals are estimated using models and the best scientific research on hand. Unlike a factory, we cannot use a device to directly measure the emissions from animals on farms and must attempt to estimate complex biological process as best as we can.

New research undertaken by Kiwi scientists show that urine deposited by livestock on hilly terrain spreads over a larger area and is therefore able to be better absorbed by the soil. This coupled with the distinct microbial makeup of hill soil results in less nitrogen being lost to the atmosphere as nitrous oxide emissions.

Rather than representing a decrease in N2O emissions for this year, this research shows that New Zealand nitrous oxide emissions have been overestimated since records started to be kept in 1990.

"The new research results in a 1,700 kt CO2-e reduction in agricultural nitrous oxide emissions estimated for 2017, an almost 20% reduction," Hoggard says.

"The bulk of these reductions come from sheep and beef livestock on steep slopes, but a lack of data resulted in the assumption being made that all dairy cattle are located entirely on flat terrain. We encourage the researchers and officials to continue to work with the agriculture industry in New Zealand in order to also make this innovative research applicable to Kiwi dairy farmers."

This research results in hill country sheep and beef nitrous oxide emissions being reduced by about two-thirds and one-third respectively in the emissions inventory back to 1990.

"Farmers across New Zealand are committed to improving environmental outcomes at home, while continuing to provide sought-after and nutrition packed food across the globe. This research highlights the fundamental importance of accurate data in managing environmental outcomes, such as greenhouse gas emissions.

"New Zealand is at the cutting edge of agricultural climate change research. Federated Farmers encourages researchers and officials to continue their hard work towards more accurately understanding the wicked problem of climate change that is facing farmers, along with all New Zealanders."

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