What GHG reduction options are more than 5 years away?

Some key research supported by the NZAGRC and PGgRc is now at, or approaching, proof of concept stage; other research is still developing fundamental understanding to identify future options. Results from laboratory or experimental settings so far are promising, but scientists are attempting world firsts here and even after proof of concept has been obtained in an animal trial, it could take five years or more before the
new technologies under development can be used widely.


'New Zealand’s predominantly grazing system means that an inhibitor could at best be given twice daily (restricting its use to
intensive dairy systems) or through a bolus (capsules that can be swallowed safely by the animal and release the inhibitor slowly
over a time of days to months).

Many thousands of compounds have been screened and more than 100 target compounds have been analysed in the laboratory; the top five to ten compounds have been tested since 2014 in animal trials in New Zealand. Some have shown promising first results with methane reductions of 30% or more, albeit so far only in short-term trials of 2-16 days. The key for New Zealand is to find inhibitors that are effective at low concentrations (for ease of administration) for pasture-based diets, are low cost, have low toxicity, carry no food safety risks and have no negative effects on productivity. While development of a suitable compound and release mechanism may be feasible sooner, ensuring that there are no residues or negative effects on productivity, and that the compound does not conflict with the expectations of New Zealand’s key export markets will take more time. On current progress, the commercial availability of an inhibitor suitable for use on New Zealand farms is expected to take until 2023 or later.

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New Zealand scientists are working to produce a vaccine that stimulates the animal to produce antibodies that suppress key methane-generating microbes in the rumen of livestock.

Prototype vaccines have demonstrated that they can generate antibodies that can alter the microbial populations and methane production in laboratory studies. Further trials are underway to demonstrate that these have an effect on methane emissions in both sheep and cattle. A vaccine would have to achieve a minimum 20% emissions reduction per animal, without reducing productivity, to be worthwhile developing.

Another line of enquiry is the use of nanobeads, microscopic beads produced by bacteria, to carry enzymes than can suppress methane-generating microbes in the rumen. While still at the fundamental inquiry stage, such approaches hold promise because they offer new and additional ways of interrupting methane production in the rumen and that could be integrated with other technologies.

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Wherever pilot studies identify plants that help lower greenhouse gas emissions, this offers two avenues for further development: the active compound that influences methane or nitrous oxide emissions could be isolated and produced commercially for use as a feed additive or the trait that generates the compound could be incorporated into other pasture species through plant breeding programmes. Both approaches would be expected to take significant time for development even after the active compound has been identified and its mode of action understood. Work is starting to identify naturally occurring nitrification inhibitors that could reduce nitrous oxide emissions without introducing new chemicals into the food chain.

It may also be possible to develop pasture species that requires less nitrogen in the first place. So far, research has identified a gene that could support the breeding of higher yielding ryegrass cultivars that do not need as much nitrogen and thus could further help reduce fertiliser inputs. There is potential to incorporate such low greenhouse gas traits into pasture. Read more


Soil microbes play a crucial role in the transformation of dung, urine and fertiliser into undesired nitrate or nitrous oxide, or into beneficial or at least harmless forms of nitrogen. Research is underway in New Zealand and elsewhere to better understand how soil microbial communities differ depending on soil type, climate and pasture management, and to see if changes in management practice could promote those organisms that reduce or bypass environmentally negative outcomes. For example, some plants encourage microbial processes that reduce nitrate to inert and environmentally harmless nitrogen gas, and work is beginning to see if these properties can be enhanced and exploited through pasture management or forage breeding. Read more


If more carbon can be absorbed and kept in the soil, this could offset greenhouse gas emissions to the atmosphere. This is particularly challenging in New Zealand when soil carbon stocks are already high, and it is equally important to ensure any new management practices aimed at enhancing production do not result in carbon losses from soil. For many management practices, their long-term impact on soil carbon remains anecdotal and/or highly dependent on local conditions including management history. Research is testing the effect of a range of management practices at different sites, and is developing models and measurement techniques to understand and test options for different conditions and locations. Short term changes in carbon stocks are not necessarily a good indicator of the long-term potential for grasslands to store carbon, making long-term modelling essential to develop robust advice.

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