Plant and Soil

, Volume 61, Issue 1, pp 7–26

Changes of pH across the rhizosphere induced by roots

Authors

  • P. H. Nye
    • Department of Soil and Plant NutritionUniversity of Western Australia
Article

DOI: 10.1007/BF02277359

Cite this article as:
Nye, P.H. Plant Soil (1981) 61: 7. doi:10.1007/BF02277359

Summary

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 pHCation-anion balanceSoil acidity diffusion coefficientCO2 pressureRoot-Soil interface

Copyright information

© Martinus Nijhoff/Dr W. Junk Publishers 1981