Plant and Soil

, Volume 117, Issue 2, pp 185–193

Root-induced nitrogen mineralisation: A theoretical analysis

  • David Robinson
  • Bryan Griffiths
  • Karl Ritz
  • Ron Wheatley


The possibility is examined that carbon (C) released into the soil from a root could enhance the availability of inorganic nitrogen (N) to plants by stimulating microbial activity. The release of soluble C compounds from roots is assumed to occur by one of two general processes: cortical cell death or exudation from intact cells. On the basis of several assumptions chosen to allow maximal amounts of N mineralisation to be calculated, greater amounts of net N mineralisation are theoretically possible at realistic soil C:N ratios of bacteria are grazed by predators such as protozoa, than if bacteria alone are active. More N is mineralised when the substrate released from the root has a high C:N ratio (as in cell death) than when it is relatively N-rich. The amounts of N that a root might realistically cause to be mineralised are unlikely to account entirely for high nitrate inflow rates that have been measured experimentally. However there are circumstances in which the loss of C from roots is essential if any N is to be mineralised and obtained by plants.

Key words

carbon exudation mineralisation nitrogen rhizosphere root uptake 


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Copyright information

© Kluwer Academic Publishers 1989

Authors and Affiliations

  • David Robinson
    • 1
  • Bryan Griffiths
    • 2
  • Karl Ritz
    • 3
  • Ron Wheatley
    • 3
  1. 1.Department of Physiology and Crop ProductionScottish Crop Research InstituteDundeeUK
  2. 2.Department of ZoologyScottish Crop Research InstituteDundeeUK
  3. 3.Department of Mycology and BacteriologyScottish Crop Research InstituteDundeeUK

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