AgResearch forage scientist Arjan Jonker acknowledges finding lower methane-emitting feeds is one of agriculture’s “wicked problems”, but says the AgResearch team is well-advanced in understanding what feeds can produce less ruminant methane.
AgResearch forage scientists are working alongside their livestock research colleagues on potential pasture types that may play a key role in helping the sector lower its methane emissions.
With both crops comprising most of the sheep’s diet, the researchers have achieved methane emission reductions of 20-30%.
Running trials for as long as 15 weeks has not revealed any compromise to animal health and productivity.
“This is definitely proving to be a viable option, but is still obviously at the research end of the spectrum,” Jonker said.
The downside of the feed option is cropping results in mineralisation on nitrogen in the soil with consequent nitrous oxide emissions, but net gas loss is still proving to be lower under the regime.
“And farmers are required to actually deliver reduced methane gas, it can’t be offset simply by planting trees,” he said.
Some early trial work has also been conducted on plantain, already identified for its ability to generate less nitrates once consumed by stock. These trials have identified some promise in lowering methane emissions.
“But it is a question of how much plantain do you need to get that reduction,” he said.
Work by DairyNZ has shown to achieve significant lower nitrate loss benefits, at least 30% of plantain is needed in a pasture sward.
AgResearch scientists have also been working on endophyte research to identify what naturally occurring fungi may offer some solutions to lower gas emissions. Patented endophytes already offer crop protection, like AR37 does to rye grasses.
“There is no clear indication yet that there is one that will help with lower methane. There are thousands of endophytes, and the challenge is to find one that does not have a negative effect on livestock health or performance. What may look good in the lab does not always translate to apply in animals in the field,” he said.
Comparative trials between conventional ryegrass, a tetraploid ryegrass and a high sugar ryegrass have highlighted the challenge in delivering a consistently low-emitting grass.
“Both the tetraploid and the high sugar grass did produce less methane than the conventional ryegrass, but there are variances within seasons, depending how the grasses are growing,” he said.
Outlier work is also examining condensed tannin clovers that have lower methane and nitrous oxide losses. Conventional clovers contribute similar amounts per kilogram of dry matter in methane to ryegrass.
Plants like Lotus corniculatus and Sulla could prove useful, but can be difficult to grow and also get good yields from, not having been subject to the crop improvement conventional clovers have enjoyed over generations.
Overall, Jonker is optimistic about the results science can deliver in coming years.
However, he maintains the biggest challenge for researchers seeking to develop lower-emitting, high-producing forage and pastures may lie more in how those improvements are accounted for, than in coming up with the solutions themselves.
“But the challenge is if the reductions are achieved, how will the Government and authorities account for those mitigations?” he asked.
“Farmers need a means to recognise whatever reductions they have made.”
