Rhizodeposition-induced decomposition increases N availability to wild and cultivated wheat genotypes under elevated CO2

Marie Anne de Graaff, Chris Van Kessel, Johan Six

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

Elevated CO2 may increase nutrient availability in the rhizosphere by stimulating N release from recalcitrant soil organic matter (SOM) pools through enhanced rhizodeposition. We aimed to elucidate how CO2-induced increases in rhizodeposition affect N release from recalcitrant SOM, and how wild versus cultivated genotypes of wheat mediated differential responses in soil N cycling under elevated CO2. To quantify root-derived soil carbon (C) input and release of N from stable SOM pools, plants were grown for 1 month in microcosms, exposed to 13C labeling at ambient (392 μmol mol-1) and elevated (792 μmol mol-1) CO2 concentrations, in soil containing 15N predominantly incorporated into recalcitrant SOM pools. Decomposition of stable soil C increased by 43%, root-derived soil C increased by 59%, and microbial-13C was enhanced by 50% under elevated compared to ambient CO2. Concurrently, plant 15N uptake increased (+7%) under elevated CO2 while 15N contents in the microbial biomass and mineral N pool decreased. Wild genotypes allocated more C to their roots, while cultivated genotypes allocated more C to their shoots under ambient and elevated CO2. This led to increased stable C decomposition, but not to increased N acquisition for the wild genotypes. Data suggest that increased rhizodeposition under elevated CO2 can stimulate mineralization of N from recalcitrant SOM pools and that contrasting C allocation patterns cannot fully explain plant mediated differential responses in soil N cycling to elevated CO2.

Original languageEnglish
Pages (from-to)1094-1103
Number of pages10
JournalSoil Biology and Biochemistry
Volume41
Issue number6
DOIs
StatePublished - Jun 2009

Keywords

  • C
  • N
  • Elevated CO
  • Genotypes
  • N mineralization
  • Rhizodeposition

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