Plant and Soil

, Volume 61, Issue 1–2, pp 7–26 | Cite as

Changes of pH across the rhizosphere induced by roots

  • P. H. Nye


Plants that absorb nitrogen as NO3 tend to raise the pH in the rhizosphere. Those absorbing nitrogen as NH4+ or N2 lower the pH. The change in pH near the root surface may be calculated approximately from the H+ or HCO3 efflux and radius of the root; and the pH buffering capacity, moisture content, initial pH and pCO2 of the soil. An accurate equation, solved numerically, also takes account of root hairs, mass flow and slow acid-base reaction in the soil. The pH at the root surface will often differ from the pH a few mm away by 1–2 units.

Key Words

Rhizosphere pH Cation-anion balance Soil acidity diffusion coefficient CO2 pressure Root-Soil interface 


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Copyright information

© Martinus Nijhoff/Dr W. Junk Publishers 1981

Authors and Affiliations

  • P. H. Nye
    • 1
  1. 1.Department of Soil and Plant NutritionUniversity of Western AustraliaAustralia

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