Plant and Soil

, Volume 26, Issue 3, pp 445–453

Phosphate diffusion in soil and uptake by plants

III. P31-movement and uptake by plants as indicated by P32-Autoradiography
  • D. G. Lewis
  • J. P. Quirk

DOI: 10.1007/BF01379565

Cite this article as:
Lewis, D.G. & Quirk, J.P. Plant Soil (1967) 26: 445. doi:10.1007/BF01379565


The distribution of P32 within growing wheat roots and in the surrounding soil was assessed by autoradiography for Seddon soil at three levels of added phosphate. Successive autoradiographs showed that the zone of depletion around the root was influenced only slightly by time. However, for all levels of phosphate addition the zone of depletion was similar in size extending approximately 1 millimetre from the surface of the root.

Subsequent examination of roots removed from these soils revealed numerous root hairs of a similar length (1 mm), suggesting that in these soils, root morphology influences the size of the depletion zone more than diffusion rates within the soil. Diffusion data for the soils used suggest that movement by this means is very slow. However, calculations are given to show that the depletion zone can be rapidly and effectively exploited by diffusive movement radial to the root hairs even when the measured diffusion coefficients are quite small.

Copyright information

© Martinus Nijhoff 1967

Authors and Affiliations

  • D. G. Lewis
    • 1
  • J. P. Quirk
    • 1
  1. 1.Department of Agricultural Biochemistry and Soil Science, Waite Agricultural Research InstituteThe University of AdelaideAdelaide
  2. 2.Department of Soil Science and Plant Nutrition, Institute of AgricultureThe University of Western AustraliaNedlands