Plant and Soil

, Volume 285, Issue 1, pp 221–231

Significance of organic nitrogen acquisition for dominant plant species in an alpine meadow on the Tibet plateau, China

Authors

    • Institute of Geographical Sciences & Natural Resources ResearchThe Chinese Academy of Sciences
    • Institute of Soil Science and Land EvaluationUniversity of Hohenheim
  • Hua Ouyang
    • Institute of Geographical Sciences & Natural Resources ResearchThe Chinese Academy of Sciences
  • Yakov Kuzyakov
    • Institute of Soil Science and Land EvaluationUniversity of Hohenheim
    • Department of Agroecosystem ResearchUniversity of Bayreuth
  • Andreas Richter
    • Department of Chemical Ecology and Ecosystem ResearchVienna Ecology Centre University of Vienna
  • Wolfgang Wanek
    • Department of Chemical Ecology and Ecosystem ResearchVienna Ecology Centre University of Vienna
ORIGINAL PAPER

DOI: 10.1007/s11104-006-9007-5

Cite this article as:
Xu, X., Ouyang, H., Kuzyakov, Y. et al. Plant Soil (2006) 285: 221. doi:10.1007/s11104-006-9007-5

Abstract

Though the potential of plants to take up organic N (e.g., amino acids) is well established, the true significance of organic N acquisition to plant N nutrition has not yet been quantified under field conditions. Here we demonstrate that organic N contributes significantly to the annual N uptake of three dominant plant species (Kobresia humilis, Saussurea superba and Stipa aliena) of alpine meadows on the Tibet Plateau, China. This was achieved by using double-labelled (14C and 15N) algae as a source for slow and continuous release of amino acids, and tracing both labels in the above- and below-ground plant biomass. Four months after addition of algae, between 0.5% and 2.6% of 14C and 5% and 14% of 15N from added algae were recovered in the plants, which translate into an uptake of organic N between 0.3 mg N m−2 and 1.5 mg N m−2. The calculated contribution of organic N to total N uptake was estimated to range between 21% and 35% for K. humilis, and between 13% and 21% for S. aliena and S. superba, respectively, implying that organic N uptake by grassland plants is quantitatively significant under field conditions in the studied alpine meadows. This finding has important ecological implications with regard to competition for organic N between microorganisms and plant roots.

Keywords

Organic N uptake14C15NAlpine grasslandN acquisitionSpirulina

Copyright information

© Springer Science+Business Media B.V. 2006