Maize rhizosphere priming: field estimates using 13C natural abundance

Amit Kumar, Yakov Kuzyakov, Johanna Pausch

Research output: Contribution to journalArticlepeer-review

87 Citations (Scopus)

Abstract

Introduction: Root-mediated changes in soil organic matter (SOM) decomposition, termed rhizosphere priming effects (RPE), play crucial roles in the global carbon (C) cycle, but their mechanisms and field relevance remain ambiguous. We hypothesize that nitrogen (N) shortages may intensify SOM decomposition in the rhizosphere because of increase of fine roots and rhizodeposition. Methods: RPE and their dependence on N-fertilization were studied using a C3-to-C4 vegetation change. N-fertilized and unfertilized soil cores, with and without maize, were incubated in the field for 50 days. Soil CO2 efflux was measured, partitioned for SOM- and root-derived CO2, and RPE was calculated. Plant biomass, microbial biomass C (MBC) and N (MBN), and enzyme activities (β-1,4-glucosidase; N-acetylglucosaminidase; L-leucine aminopeptidase) were analyzed. Results: Roots enhanced SOM mineralization by 35 % and 126 % with and without N, respectively. This was accompanied by higher specific root-derived CO2 in unfertilized soils. MBC, MBN and enzyme activities increased in planted soils, indicating microbial activation, causing positive RPE. N-fertilization had minor effects on MBC and MBN, but it reduced β-1,4-glucosidase and L-leucine aminopeptidase activities under maize through lower root-exudation. In contrast, N-acetylglucosaminidase activity increased with N-fertilization in planted and unplanted soils. Conclusions: This study showed the field relevance of RPE and confirmed that, despite higher root biomass, N availability reduces RPE by lowering root and microbial activity.

Original languageEnglish
Pages (from-to)87-97
Number of pages11
JournalPlant and Soil
Volume409
Issue number1-2
DOIs
Publication statusPublished - Dec 1 2016
Externally publishedYes

Keywords

  • C/Cvegetation change
  • Enzyme activities
  • Microbial biomass
  • N-fertilization
  • Soil CO
  • SOM decomposition

ASJC Scopus subject areas

  • Soil Science
  • Plant Science

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