Low Methane Pasture Species Key to Reducing NZ Farm Emissions

John Caradus who is chief technology officer for Grasslanz Technology and someone who has spent a lifetime in plant breeding says the best starting point to reduce GHG emissions in New Zealand is at the pasture level and looking at what the animals eat.

Much research is already underway in this area at Grasslanz, which is now part of the Bioeconomy Science Institute, in collaboration with other organisations both in NZ and offshore.

Alternative Pasture Species Under Investigation

He says the two predominant pasture species grown on NZ farms are perennial ryegrass and white clover, but notes that there are other species that could be used such as tall, meadow fescue, cocksfoot and a number of minor legumes.

"But one of the problems with some of the other pasture legumes is that they don't compete well in our grazed swards. So, if we could find a way of getting a legume such as Lotus corniculatus, also known as birds-foot trefoil, into our grazed pastures that would make a difference," he says.

Caradus says birdsfoot trefoil can produce condensed tannin of the appropriate type and amount in its leaves.

He adds that if we could integrate these types of species into our perennial ryegrass sward it would aid in reducing methane production and probably nitrous oxide too.

Mixed Species Pastures Gaining Research Attention

The idea of mixed species is one that is being closely researched and trialled at present.

For example, Massey University and others are looking at what difference plantain, chicory and white clover can have on reducing GHG emissions.

There is also work going on in the field of genetics to produce animals with low methane emitting traits.

Calls for Science Funding Aligned with Farmer Needs

While new research is taking place, much of this can be traced back to work done by agricultural scientists in the 1970s.

Caradus believes this was due to the funding regime at the time when scientists had more control over their research than now, whereby the funder - by default the Government - sets very tight limits on what research can be done.

However, under the new funding system that is about to get underway, there is hope that science funding will be better aligned with farmers' needs.

"However, the reality is that today, in terms of pasture development and management, we are still relying heavily on the work done by the scientists in the 1970s," says Caradus.

Managing Grass

While scientists can develop new grass species that reduce methane and nitrous emissions in animals, success at a farm level depends on how the pasture is managed, says John Caradus.

He says high stocking rates - particularly on dairy farms - is not conducive to pasture persistence and therefore the gains available in grasses cannot be realised.

"Pasture persistance is a real issue. This is because of the impact of droughts and insect pests. Even with fungal endophytes in ryegrass which protect the plant from insects. It's that combination plus overgrazing that can drive down the persistance of our ryegrass pastures," he says.

Caradus says it's a matter of getting farmers to back off a little on grazing pressure.

Developing new methane reducing legumes is not easy he says because our major species of ryegrass and tall fescue grass don't have the secondary metabolites that will reduce GHG emissions. One option for this he says might be to use gene editing or genetic modification.

For Caradus and the teams of scientists working to develop new grass species it is encouraging that in general New Zealand farmers are willing to try new opportunities and can be regarded as early adopters.

He says this became evident when a new endophyte strain of ryegrass - AR1 which protects the plant from Argentine stem level and reduces ryegrass staggers - was introduced in the early 2000s.