Trialling serradella as an option for permanent pasture systems

Research is underway to determine the best agronomy practices, including at a trial site in Bookham, however, a lot is already known about the legume.

Project lead Rebecca Hailing, CSIRO, Canberra, said there were several potential benefits of serradella.

"Work we've done under a previous project demonstrated that serradella had a significantly lower requirement for phosphorus fertilisers than sub clovers," she said.

"We found the serradella would yield as well as sub clover, but with about 30 per cent less applied phosphorus.

"They are adapted to the cooler tablelands type climates and can grow in these regions well on sandy through to duplex soil types."

Ms Hailing said serradella had also shown to be acid soil tolerant, have a low bloat risk and low oestrogenic activity, as well as drought tolerant.

The first part of the project had been to identify the suitability of the cultivars for medium to high rainfall zones, with most having been developed in Western Australia with maturity types too early for the target environments.

Ms Hailing said the cultivars needed to have hard seed traits to allow them to self regenerate in a permanent pasture setting, along with good dry matter production.

"Across our experiments in NSW we've consistently found the yellow serradella cultivar, Avila, is standing out in terms of having the best persistence," she said.

"And in the Yass region we've also found that a cultivar of French serradella, called Rosa, is also regenerating well."

Ms Hailing said the next step was to work out how to successfully establish and manage the serradella.

"We're looking at things like sowing rates, companion species, what type of seed to use and when to sow it, and also the requirements for other nutrients like sulphur, and potassium," she said.

There are several trial sites from the Northern Tablelands to the Monaro in NSW, as well as the midlands region of Tasmania.

Ms Hailing said at the Bookham site, established in December 2023, they were looking at whether serradella could be introduced to an existing low fertility native pasture by broadcasting the pod.

"We're using an experimental rate of 30kg/ha and 60kg/ha to test the principle and work back from there to see what's economical," she said.

Additional treatments include broadcast pod then incorporated to act as a sown control as well as a plot where the Microlaena was sprayed out prior to broadcasting to see if setting back the existing pasture helps the serradella establish.

She also said they were investigating whether pods, instead of bare seeds, could work in a spring sowing scenario.

Other experiments conducted at other sites include companion planting with chicory and cocksfoot and testing the sulphur and potassium responses.

While research was ongoing, Ms Hailing said for those looking to use serradella there were some considerations, including currently limited commercial availability of the identified cultivars.

"Supply is meant to be increasing in the next one to two years so if you do go out looking to buy serradella you need to be mindful that what you're most likely to be offered is possibly a shorter season type from WA or something that might be completely soft seeded," she said.

Ms Hailing said due to the advantage of using the harder seed serradella for long term persistence, they had seen a gap in the second year regeneration because the seed had not softened yet from the first year.

"What we're finding as part of the project is that it's really important to set everything up in the first year to get a good stand of serradella and maximise your seed set so that small proportion of seed that is available to germinate that has softened in that first year comes back in sufficient numbers," she said.

Ms Hailing said there was a lack of broadleaf weed control options for serradella, so it was important to have good weed control and paddock preparation prior to sowing.

She said another key to successful establishment was to exclude stock in the first year.

"Then the rule of thumb is every two or three years depending on how season conditions are, so exclude stock to allow them to replenish that seedbank," she said.

The project is a collaboration between MLA, CSIRO, NSW Department of Primary Industries and the University of Tasmania.