Tips and Tactics: Legumes and Nitrogen Fixation

Published: 1 Jun 2017

Use the four-step 'nod check' to assess your legume nodulation

For the current legume crop to gain nitrogen (N), and to increase soil N for future rotations, legumes need to be adequately nodulated by root nodule bacteria (rhizobia). Nodulation is important for lupin, lentil, field pea, faba bean, vetch and chickpea crops and for pastures (e.g. medic).

Key Points

  • All legumes sown by Australian growers require specific root nodule bacteria (rhizobia) to fix nitrogen (N).
  • Roots need to have adequate numbers of active nodules to ensure optimal amounts of N will be fixed by the rhizobia.
  • Nodules can form from soil rhizobia or through inoculation.
  • Growers should investigate the extent of nodulation in grain and pasture legumes, irrespective of whether the seed was inoculated or not.
  • Conduct ‘nod checks’ in late winter or early spring; ideally 10–12 weeks after sowing.
  • Aim for a score of ‘adequate’ to be confident your crops have a sufficient number of nodules to fix abundant N.

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Region: South; West

GRDC Project Code: UA00138,