loading page

Root Exudates Alters Nutrient Transport in Soil
  • +2
  • Amit Paporisch,
  • Harel Bavli,
  • Rachel J Strickman,
  • Rebecca B Neumann,
  • Nimrod Schwartz
Amit Paporisch
The Hebrew University of Jerusalem

Corresponding Author:amit.paporisch@mail.huji.ac.il

Author Profile
Harel Bavli
The Hebrew University of Jerusalem
Author Profile
Rachel J Strickman
University of Wasington
Author Profile
Rebecca B Neumann
University of Washington
Author Profile
Nimrod Schwartz
Hebrew University of Jerusalem
Author Profile


Root exudates alter the rhizosphere’s physical properties, but the impact that these changes have on solute transport is unknown. In this study, we tested the effects of chia mucilage and wheat root exudates on the transport of iodide and potassium in saturated or unsaturated soil. Saturated solute breakthrough experiments, conducted in loamy sand soil or coarser textured quartz sand, revealed that increasing the exudate concentration in soil resulted in increasingly non-equilibrium solute transport. This behavior was demonstrated by an initial solute breakthrough after fewer pore volumes and the arrival of the peak solute concentration after greater pore volumes in soil mixed with exudates compared to soil without exudates. These patterns were more pronounced for the quartz sand than in the loamy sand soil and in soil mixed with mucilage than in soil mixed wheat root exudates. Parameter fits to these breakthrough curves with a mobile-immobile transport model indicated the fraction of immobile water increased as the concentration of exudates increased. For example, in quartz sand the estimated immobile fraction increased from 0 without exudates to 0.75 at a mucilage concentration of 0.2%. The solutes’ breakthrough under unsaturated conditions was also altered by the exudates, demonstrated by a smaller volume of water extracted from soil mixed with exudates, compared to soil without exudates, before the arrival of the peak solute concentration. The results indicate that exudates alter the rhizosphere’s transport properties; we hypothesize that this is due to exudates creating low-conducting flow paths that result in a physical non-equilibrium solute transport.
Oct 2021Published in Water Resources Research volume 57 issue 10. 10.1029/2021WR029976