Overview

Biological nitrogen fixation, where rhizobia in legume root nodules convert atmospheric di-nitrogen into ammonia for plant growth is one of the great success stories in applied soil biology.

In an era of rising costs, the role of rhizobia to "fix" biological nitrogen is more important than ever. The replacement of nitrogen fertilizer with biologically-fixed nitrogen is estimated to save Australian agriculture approximately $3bn per year. Legumes provide an economically and environmentally sustainable source of nitrogen and usually soil nitrogen increases where they are grown.

For over 50 years, the Australian Inoculants Research Group (and its predecessors) located at Gosford Primary Industries Institute, have controlled and maintained the quality of legume inoculants.

Australian farmers have access to the best legume inoculants in the world

So why are Australian inoculants so good?

• AIRG under the control of the NSW Department of Industry and Investment (Industry & Investment NSW), Science and Innovation Division, Soils and Organics Unit, has an Australia-wide mandate to ensure that the country’s farmers and producers have access to high quality legume inoculants and inoculant products containing prescribed numbers of effective root-nodule bacteria (rhizobia)
• There is a continual commitment to legume inoculant research by government, university and the various R&D funding bodies
• AIRG has a new MOU with the University of Sydney for collaborative R&D expansion
• AIRG bridges the gap between research and commercial production of legume inoculants
• Consumers can now be even more confident of the superior quality of Australian inoculants thanks to the AIRG's new Code of Practice which establishes a set of protocols and independent testing standards for assessing legume inoculant products for quality. To read about the National Code of Practice and Quality Trademark, download the document below;
  

What does AIRG do?

Ensures that only high quality legume inoculants are sold in Australia

Inoculant quality is determined by the effectiveness of the strain of rhizobia to fix nitrogen and the number of live rhizobia. AIRG currently assesses selected submitted batches produced by Australian and overseas manufacturers for both of these criteria. Each year, up to 400 batches of peat inoculants are tested.

Each batch of inoculant is assessed to ensure that inoculants released for sale have:

- the approved and correct strain of rhizobia for the legume group
- high numbers of live rhizobia. The standard for all inoculants is 1,000 million/gram of fresh peat, except Lotononis
- nil or minimal numbers of other contaminant micro-organisms
- optimum moisture potential for growth and survival of the rhizobia after manufacture and during storage
- the strain’s capacity for nitrogen fixation with its legume test plant.

Only when these standards have been met, is the batch approved by AIRG for sale, with an expiry date.

Supply the commercial manufacturers with “Mother” cultures of the rhizobia used in inoculants

Each year, AIRG supplies a fresh set of recommended inoculant strains for temperate and tropical legumes to the inoculant manufacturers. They then produce commercial inoculants from these cultures. These strains must meet stringent criteria before being released by AIRG.

AIRG also holds and distributes a limited number of non-rhizobial cultures used in commercial manufacture.

Rhizobial strain testing and approval for use in inoculants

- AIRG has established protocols for the selection and recommendation of strains of rhizobia for inoculants, involving inputs from Australian scientists from each of the mainland states engaged in rhizobia research.

- Strain evaluation is an on-going activity. AIRG is committed to ensure the most effective strains are matched with new legume species and cultivars. With expansion of legume improvement programs around the country, strain evaluation has become even more critical. Currently, there are more than 35 strains covering 90 species of legume approved by AIRG.

- AIRG maintains the policy of having single strain inoculants for all legumes.

- AIRG plays its part in the national strain testing program. In recent years, AIRG has tested new strains for pea, lupin, faba bean, biserrula, lucerne, annual medic, lotus, serradella and red, arrowleaf, crimson and subterranean clover.

Maintenance of back-up strains

AIRG holds more than 1,700 strains of rhizobia in its collection which are maintained as a germplasm bank for legumes that as yet have no recommended inoculant strain.

Troubleshoot problems in manufacture and distribution of rhizobial inoculants

Problems sometimes occur, causing low numbers of rhizobia in the peat-based inoculants, e.g. saline peat, or loss of effectiveness of the rhizobia itself, e.g. strain variation. AIRG plays an active role in finding solutions to such problems.

The benefits of inoculation

Inoculating legumes is cheap, costing less than $5/ha, yet can result in an extra $200-300 worth of N in the crop or pasture. For example, inoculation of soybean on the Liverpool Plains, NSW increased nodulation from almost zero to 100%. Grain yields were increased by approximately 1.5 t/ha, worth $600/ha, dwarfing the $5/ha cost of inoculation.

The bottom line - avoiding nodulation failure in the paddock

The cost of legume nodulation failure because seed was not inoculated or because of faulty inoculants is substantial. Australian farmers inoculate about 2.5 million ha or 50% of the legumes sown annually. Essentially all of the 3-4 million tonnes of nitrogen fixed annually by legumes growing on about 25 million ha of land can be attributed to either current or past inoculation (Brockwell 2004; Herridge, unpublished).
Inoculation has played a key role in the success of legumes in this country and AIRG and its predecessors, ALIRU, AIRCS and U- DALS have ensured that Australian farmers and producers have always had access to inoculants of the highest quality.

What if the market was suddenly flooded with low quality inoculants either produced locally or imported from overseas?

The simple answer is that such a development would put at risk the production of grains such as lupin, chickpea, faba bean, pastures and livestock, and would cost the individual farmer or producer money. The cost of a nodulation failure of 100 hectares of soybean could exceed $60,000. Clearly, the continuing and uninterrupted use of high quality legume inoculants has a very large economic benefit to Australian farmers. The use of AIRG quality assessed and approved inoculants is strongly recommended.

AIRG is proudly funded by

Becker Underwood Pty Ltd
New Edge Microbials Pty Ltd
Novozymes Biologicals, Ltd
Grains Research & Development Corporation (GRDC)
Rural Industries Research & Development Corporation (RIRDC)
NSW Department of Industry and Investment (Industry & Investment NSW)

For further information

Contact:
Elizabeth Hartley or Greg Gemell at:
AIRG, Gosford Primary Industries Institute
Locked Bag 26 Gosford NSW 2250
Ph: 02 4348 1948 Fax: 02 4348 1910
e-mail: greg.gemell@industry.nsw.gov.au