Aktualisiert: 8. Juli 2020
This Legumes Translated Practice Note 'Biological nitrogen fixation in legumes: Understanding the process' was developed from partners, Agrobioinstitute (ABI) in Bulgaria. The note explains the process of nitrogen fixation and includes some key practice points. It was elaborated in the framework of the Legumes Translated project.
A close-up photograph of a split nodule showing the characteristic pink colour (left) an indication of a successful establishment of the rhizobium and active biological nitrogen fixation, photo: www.gartensoja.de. Nodulated roots of soybean plants from the field (right), photo: Leopold Rittler (Donau Soja).
In nature, biological nitrogen fixation (BNF) provides most of the reactive nitrogen that is required for protein formation and plant growth. Legumes host BNF, so growing a successful grain legume crops depends to a great extent on the amount of nitrogen fixed in the nodules of their root systems.
Including legumes in crop rotations is a cheap and affordable way to enrich soils with nitrogen. Nitrogen fixed by legumes is an alternative to synthetically-fixed nitrogen in fertilisers. Because of BNF, introducing legumes into cropping systems reduces some of the damaging emissions from the agricultural nitrogen cycle, especially nitrous oxide (N2O) which is a potent greenhouse gas.
Key practice points:
Establish the symbiosis between the nitrogen - fixing bacteria and the host legume plant. It is important to have the right bacteria because each legume has a specific type of symbiotic bacteria in the family Rhizobiaceae.
Protect the root nodules - Pea and bean weevil (Sitona spp.) adults eat the leaves but this has little effect of the crop yield. Integrated pest management of Sitona spp. including the use of biocontrol and pheromone- baited traps is required is some situations
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