Soil diffusive fluxes constitute the bottleneck to tree nitrogen nutrition in a Scots pine forest

Author(s)

Olusegun Ayodeji Oyewole, Sandra Jamtgard, Linda Gruffman, Erich Inselsbacher, Torgny Näsholm

Abstract

In nutrient poor environments, plant nitrogen (N) acquisition is governed by soil diffusive fluxes and root uptake capacities. However, the relationship between these two processes is not well understood. We explored a way of comparing the processes, enabling identification of the limiting factor for tree N acquisition.

The study comprised N-fertilized and N-limited Scots pine stands, and measurements of uptake capacities of detached tree roots and of induced soil diffusive fluxes (through in-situ microdialysis) done at the onset and the end of the growing season.

Soil N fluxes were higher at the onset than at the end of the growing season and amino acids comprised a larger fraction of N than inorganic N. N fertilization reduced root uptake capacities of NH4 (+), glycine and NO3 (-) but not of arginine. For all N compounds except NO3 (-), diffusive fluxes were significantly lower than root N uptake capacities.

Our results suggest that soil N supply in both, N-fertilized and N-limited forest stands, is dominated by amino acids, thus being the major component of plant-available N. Uptake of N appears more constrained by the diffusive fluxes of N compounds rather than root uptake capacity, except for NO3 (-).

Organisation(s)

Department of Geography and Regional Research

External organisation(s)

Swedish University of Agricultural Sciences (SLU)

Journal

Plant and Soil: international journal on plant-soil relationships

Volume

399

Pages

109-120

No. of pages

12

ISSN

0032-079X

DOI

https://doi.org/10.1007/s11104-015-2680-5

Publication date

2016

Peer reviewed

Yes

Austrian Fields of Science 2012

106030 Plant ecology, 105405 Geoecology

Keywords

Portal url

https://ucrisportal.univie.ac.at/en/publications/2aa3828e-25ae-4e7d-8536-81502895f783