Monday, 10 February 2020
Science reveals promise on the horizon
I’m often asked how long it will take scientists to come up with new technologies or practices that farmers can use to reduce their greenhouse gas emissions. It’s a fair question. Agriculture is responsible for nearly half of New Zealand’s total carbon dioxide equivalent greenhouse gas emissions, and the sector is eager to do more to reduce them.
Some farmers have already done what they can, while others are limited by their unique climate, topography, markets and infrastructure
NZAGRC funds and co-ordinates a wide range of scientific research aimed at identifying potential solutions and testing their efficacy. Unfortunately, due to the complexity of New Zealand’s farming systems, it’s a slow journey, but we’re moving in the right direction. On the next page I’ve summarised some of our most promising research. Firstly though, I must emphasise the painstaking process of gathering evidence to assess a possible new solution’s viability, which can take several years.
Challenges to finding solutions
- Will it work consistently on all farms, or all animals, under all conditions?
- How long will it take to have an effect, and will it last?
- Will the beneficial effect on emissions of one greenhouse gas be countered by a detrimental effect on another (‘pollution swapping’)?
- Will animal productivity and health, or the food chain, be affected?
Beyond the science, important considerations remain:
- What will it cost farmers to adopt this solution?
- Will that cost compromise their bottom line – or even the national economy?
- How does this solution weigh up, in terms of cost, efficacy and societal impact, against options to reduce emissions of other greenhouse gases by other sectors?
These are some of the difficult questions we must answer as a nation, to determine the specific actions that farmers could take to reduce emissions. Rest assured, however, that the New Zealand science community, in collaboration with industry-good organisations and farmers themselves, is stepping up to its part of the challenge.
The Government and industry have invested heavily in research targeting reductions in emissions of the two main agricultural greenhouse gases; methane (which is mostly belched out by ruminant animals) and nitrous oxide (the result of micro-organisms acting on nitrogen in the soil).
Promising options on the horizon
Breeding low-emitting sheep and cattle
Some individual animals emit less methane than others, and scientists have confirmed this is a genetic trait. Good progress has been made in the sheep breeding programme, and incorporation into selection indices is likely during the early 2020s. Work on breeding low-emitting cattle is just beginning.
It might also be possible to breed animals that excrete less nitrogen.
Although the primary driver of methane emissions is the quantity of feed eaten, the chemical make-up of feeds can have an influence. Different feeds can also influence the quantity of nitrogen deposited in urine and the chemical make-up of the urine.
For example, forage rape can reduce methane emissions by up to 30%. Plantain has been shown to reduce nitrogen leaching and nitrous oxide emissions. Fodder beet has also shown promising results. The benefits and applicability of alternative fodder crops such as these depend on specific farm systems, including when the feeds are used.
A methane inhibitor is a chemical compound fed to an animal to reduce the activity of micro-organisms in its rumen that produce methane. It’s highly likely that an inhibitor will be on the market by 2023. Usually an inhibitor has to be fed daily, making it unsuitable for many of our pasture-based farm systems. However, the development of slow-release formulations could change this.
A methane vaccine would, in theory, trigger an animal’s immune system to generate antibodies in saliva that reduce methane in a similar way to an inhibitor. A vaccine would be ideal for pasture-based systems, but its successful development is extremely challenging. At present, prototype vaccines work in the laboratory, but transferring that success into animals is proving elusive.
Nitrification and urease inhibitors slow down the activity of micro-organisms residing in the soil that convert nitrogen contained in fertilisers and animal excreta into nitrate and nitrous oxide. A variety of compounds are being field-tested.
"It might be a slow journey, but some of the world’s finest scientific minds are leading the way."
Work in each of these areas is making it very clear that not all farms have the same potential to reduce emissions. Some farmers have already done what they can, while others are limited by their unique climate, topography, markets and infrastructure.
It might be a slow journey, but some of the world’s finest scientific minds are leading the way. Consulting officers, environment specialists, extension staff and other rural professionals are gearing up to help through a programme funded by the Ministry for Primary Industries and NZAGRC, and there will be regular updates on progress.