Producers resuming their long-term plans for leucaena plantings following recent rains across central and southern Queensland have received a boost with the pending release of a new rhizobium inoculum.

Leucaena is a nitrogen-fixing tree legume renowned for increasing animal productivity.

The Lecuaena Network, the industry’s peak grower body, recently raised concerns after it was identified through annual testing of the leucaena rhizobium inoculum by the Australian Inoculants Research Group (AIRG) that the CB3126 strain was not performing typically and not producing effective, nitrogen fixing nodules on leucaena seedlings.

The same rhizobium inoculant is used when planting another tropical legume, Desmanthus.

However, the AIRG has now sourced a new strain of CB3126 rhizobium inoculant from the freeze-dried collection at the Centre for Rhizobium Studies at Murdoch University.

Craig Antonio, Chair of the Leucaena Network believes the new strain will allay any fears for the industry.

“The rhizobium inoculant is an essential component of growing productive stands of leucaena.  The native rhizobium bacteria that is usually present in the soil is unlikely to fix the nitrogen for which leucaena is known, so inoculation with an effective rhizobium is necessary,” Mr Antonio said.

“The treatment of the seed with the CB3126 rhizobium guarantees nitrogen fixation which has the dual benefit of assisting plant growth and returning much of that nitrogen to the soil.”

Mr Antonio conceded that despite this positive news, the concerns regarding the original rhizobium will have some effect on the industry.

“We have growers, and potential growers ready to plant almost immediately and this issue will cause some delays in rhizobium availability,” Mr Antonio said.

“The AIRG have advised us that they are currently undertaking extensive testing procedures to ensure that this strain of CB3126 is effective.”

The AIRG has issued a statement indicating that the rhizobium inoculant is unlikely to be available prior to Christmas 2017.

“As a leucaena grower myself, I can understand the frustration with not being able to get new stands planted after this rain, however, I do believe the long-term benefit of having a strain that is guaranteed to be effective is worth the short-term inconvenience,” Mr Antonio said.

The Leucaena Network is closely following the testing process and will be posting updates on the website at www.leucaena.net to ensure growers are advised immediately when the new strain of rhizobium inoculant becomes available.

Source: Meat & Livestock Australia, Leucaena Network