Abstract

Plant nutrient uptake from soil is mainly governed by diffusion and transpirationally induced mass flow, but the current methods for assessing the relative importance of these processes are indirect.We developed a microdialysis method using solutions of different osmotic potentials as perfusates to simulate diffusion and mass flow processes, and assessed how induced mass flow affected fluxes of nitrogen (N) compounds in solution and in boreal forest soil.Varying the osmotic potential of perfusates induced vertical fluxes in the direction of the dialysis membranes at rates of between 1 x 10(-8) and 3 x 10(-7) m s(-1), thus covering the estimated range of water velocities perpendicular to root surfaces and induced by transpiration.Mass flow increased N fluxes in solution but even more so in soil. This effect was explained by an indirect effect of mass flow on rates of diffusive fluxes, possibly caused by the formation of steeper gradients in concentrations of N compounds from membrane surfaces out in the soil. Our results suggest that transpiration may be an essential driver of plant N acquisition.

Keywords

amino acids; Dextran 40; diffusion; mass flow; microdialysis; nutrient availability; osmotic potential; transpiration

Published in

New Phytologist
2014, Volume: 201, number: 3, pages: 1056-1064
Publisher: WILEY-BLACKWELL

SLU Authors

• Oyewole, Olusegun Ayodeji

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Inselsbacher, Erich

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Näsholm, Torgny

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1111/nph.12553

Permanent link to this page (URI)

https://res.slu.se/id/publ/60384