A novel 13C pulse-labelling method to quantify the contribution of rhizodeposits to soil respiration in a grassland exposed to drought and nitrogen addition

Ruzhen Wang, Bahareh Bicharanloo, Milad Bagheri Shirvan, Timothy R. Cavagnaro, Yong Jiang, Claudia Keitel, Feike A. Dijkstra

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

Rhizodeposition plays an important role in below-ground carbon (C) cycling. However, quantification of rhizodeposition in intact plant–soil systems has remained elusive due to methodological issues. We used a 13C-CO2 pulse-labelling method to quantify the contribution of rhizodeposition to below-ground respiration. Intact plant–soil cores were taken from a grassland field, and in half, shoots and roots were removed (unplanted cores). Both unplanted and planted cores were assigned to drought and nitrogen (N) treatments. Afterwards, shoots in planted cores were pulse labelled with 13C-CO2 and then clipped to determine total below-ground respiration and its δ13C. Simultaneously, δ13C was measured for the respiration of live roots, soils with rhizodeposits, and unplanted treatments, and used as endmembers with which to determine root respiration and rhizodeposit C decomposition using two-source mixing models. Rhizodeposit decomposition accounted for 7–31% of total below-ground respiration. Drought reduced decomposition of both rhizodeposits and soil organic carbon (SOC), while N addition increased root respiration but not the contribution of rhizodeposit C decomposition to below-ground respiration. This study provides a new approach for the partitioning of below-ground respiration into different sources, and indicates that decomposition of rhizodeposit C is an important component of below-ground respiration that is sensitive to drought and N addition in grassland ecosystems.

Original languageEnglish
Pages (from-to)857-866
Number of pages10
JournalNEW PHYTOLOGIST
Volume230
Issue number2
DOIs
Publication statusPublished - Apr 2021
Externally publishedYes

Keywords

  • drought
  • nitrogen fertilization
  • photosynthetic carbon
  • pulse labelling
  • root exudation

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