Fixing On Nitrogen Better Rhizobium For Grain Legumes

Rhizobium bacteria able to nodulate pea, faba bean, narbon hean, vetch and lentil occur in many southern Australian soils, but are absent from some. A CSIRO research team recommends inoculation of all sowings of these crops, and of lupin and chickpeas, especially on acid soils.

These are among the results of recent field work at sites in New South Wales, South Australia and Victoria on the benefits of well-nodulated grain legumes to a succeeding wheat crop.

The field work has generated a lot of new information for a CSIRO Division of Plant Industry project aimed at maximising nitrogen fixation by all temperate grain legumes grown in Australia.

Researcher John Brockwell has the task of compiling information from the project into a comprehensive publication which targets growers and agronomists in each state. It should be available in 1994.

Did you know that...?

The project recently found that:

  • 'Pea' rhizobium, capable of nodulating pea, faba bean, narbon bean, lentil and vetch, persist very poorly in acid soils.
  • Auger inoculation is satisfactory when correctly used, but when seeds need to be treated with fungicide, spray inoculation is recommended.
  • For soil of pH 6 and higher, simple inoculation methods are sufficient.
  • For soil of pH 5-6, higher rates are essential. These can be achieved by auger or spray methods.
  • Auger-inoculated seed loses its viability, and should be re-inoculated after 4-5 days.
  • Research has led to the commercial production of a faba bean inoculant.
  • Liming dramatically improves nitrogen fixation, especially on very acid soils.