Direct estimation of mass flow and diffusion of nitrogen compounds in solution and soil

Olusegun Ayodeji Oyewole, Erich Inselsbacher, Torgny Nasholm

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed


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 × 10 -8 and 3 × 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.

Seiten (von - bis)1056-1064
FachzeitschriftNew Phytologist
PublikationsstatusVeröffentlicht - Feb. 2014

ÖFOS 2012

  • 507015 Regionalforschung