Plant and Soil

, Volume 141, Issue 1–2, pp 13–39

Biological nitrogen fixation: Investments, expectations and actual contributions to agriculture

  • Mark B. Peoples
  • Eric T. Craswell

Abstract

Inputs of biologically fixed N into agricultural systems may be derived from symbiotic relationships involving legumes and Rhizobium spp., partnerships between plants and Frankia spp. or cyanobacteria, or from non-symbiotic associations between free-living diazotrophs and plant roots. It is assumed that these N2-fixing systems will satisfy a large portion of their own N requirements from atmospheric N2, and that additional fixed N will be contributed to soil reserves for the benefit of other crops or forage species. This paper reviews the actual levels of N2 fixation attained by legume and non-legume associations and assesses their role as a source of N in tropical and sub-tropical agriculture. We discuss factors influencing N2 fixation and identify possible strategies for improving the amount of N2 fixed.

Key words

actinorhizal plants associative N2 fixation Azolla legumes rhizobia symbiotic N2 fixation 

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Copyright information

© Kluwer Academic Publishers 1992

Authors and Affiliations

  • Mark B. Peoples
    • 1
    • 2
  • Eric T. Craswell
    • 1
    • 2
  1. 1.CSIRO Division of Plant IndustryCanberraAustralia
  2. 2.TAC SecretariatFAORomeItaly
  3. 3.Australian Centre for International Agricultural ResearchCanberraAustralia

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