Inoculation pays off

Author: | Date: 27 May 2014

Image of GRDC western regional deputy chairman Mike Ewing

Inoculating legumes is a minor cost for a potentially substantial payoff in terms of extra grain or biomass yield and extra nitrogen in the soil.

Only about half the area in Western Australia grown to field pea, vetch and lupin crops is inoculated, leaving plenty of room for growers to improve the nitrogen fixing potential of these crops.

The Grains Research and Development Corporation (GRDC) is currently investing in a national rhizobium program that aims to update and improve nitrogen fixation by legumes.

One of the aims is to identify better strains of rhizobium suited to the full array of legume species (particularly new pastures) and able to survive our challenging soils and stresses such as acidity and salinity.

Work is also focused on developing application technologies that meet the demands of our evolving farming systems, including systems compatible with sowing legumes into dry soil.

The program is funding work to improve quality control of inoculum production, as rhizobia are live organisms and growers need to have confidence that the inoculum that they have purchase meets specifications.

Information, extension and training are also being provided to help growers convert research results and commercial products into effective farm practices.

During the last year, experienced WA-based practitioner Neil Ballard has addressed a series of workshops and field days, highlighting the critical issues and delivering information on how growers can achieve the full potential of legume nitrogen fixation.

From work already conducted, the GRDC has put together several publications. One of these, Inoculating legumes: a practical guide, has been through two editions in 18 months because of heavy demand. 

There is now also a ute guide available, Inoculating legumes – The Back Pocket Guide.

Getting the inoculation process right pays off, so it’s important to follow a few basic rules:

  • Use quality inoculants (the Green Tick logo is a trademark of Australian Inoculants Research Group approval);
  • Match the correct inoculant group to each legume;
  • Inoculants contain live bacteria. Make sure they are kept in moderate temperatures (less than 30°C, not frozen) away from sunlight and chemicals;
  • Sow freshly inoculated seed as soon as possible and definitely within 24 hours of inoculation;
  • Use clean potable water for dilution when using liquids or slurries, and make sure holding tanks are free from chemical and fertiliser residues;
  • Many pesticides, mineral and organic fertilisers are toxic to rhizobia and should never be mixed with rhizobia;
  • Rhizobia can be compatible with seed pickles or dressings for a limited time prior to sowing - always apply the seed dressing first and allow it to fully dry before applying the rhizobia as a second process;
  • Always use inoculants before their expiry date; Reseal opened bags of peat inoculant and use them within two weeks of first opening the bag.

For more information about inoculating legumes:

Inoculating legumes – The Back Pocket Guide can be downloaded at

Inoculating Legumes: A Practical Guide is available at

The Rhizobial Inoculants Fact Sheet is available at

GRDC Project Code COR0022

Region West