Plant and Soil

, Volume 295, Issue 1, pp 253–264

Assimilation dynamics of soil carbon and nitrogen by wheat roots and Collembola

  • Thomas Larsen
  • Antonie Gorissen
  • Paul Henning Krogh
  • Marc Ventura
  • Jakob Magid
Regular Article

DOI: 10.1007/s11104-007-9280-y

Cite this article as:
Larsen, T., Gorissen, A., Krogh, P.H. et al. Plant Soil (2007) 295: 253. doi:10.1007/s11104-007-9280-y

Abstract

It has been demonstrated that plant roots can take up small amounts of low-molecular weight (LMW) compounds from the surrounding soil. Root uptake of LMW compounds have been investigated by applying isotopically labelled sugars or amino acids but not labelled organic matter. We tested whether wheat roots took up LMW compounds released from dual-labelled (13C and 15N) green manure by analysing for excess 13C in roots. To estimate the fraction of green manure C that potentially was available for root uptake, excess 13C and 15N in the primary decomposers was estimated by analysing soil dwelling Collembola that primarily feed on fungi or microfauna. The experimental setup consisted of soil microcosm with wheat and dual-labelled green manure additions. Plant growth, plant N and recoveries of 13C and 15N in soil, roots, shoots and Collembola were measured at 27, 56 and 84 days. We found a small (<1%) but significant uptake of green manure derived 13C in roots at the first but not the two last samplings. About 50% of green manure C was not recovered from the soil-plant system at 27 days and additional 8% was not recovered at 84 days. Up to 23% of C in collembolans derived from the green manure at 56 days (the 27 days sampling was lost). Using a linear mixing model we estimated that roots or root effluxes provided the main C source for collembolans (54−79%). We conclude that there is no solid support for claiming that roots assimilated green manure derived C due to very small or no recoveries of excess 13C in wheat roots. During the incubation the pool of green manure derived C available for root uptake decreased due to decomposition. However, the isotopic composition in Collembola indicated that there was a considerable fraction of green manure derived C in the decomposer system at 56 days thus supporting the premise that LMW compounds containing C from the green manure was released throughout the incubation.

Keywords

Dissolved organic carbonGreen manure15N13CLinear mixing modelFolsomia fimetariaProisotoma minutaProtaphorura armata

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Thomas Larsen
    • 1
    • 2
  • Antonie Gorissen
    • 3
  • Paul Henning Krogh
    • 2
  • Marc Ventura
    • 4
  • Jakob Magid
    • 1
  1. 1.Plant Nutrition and Soil Fertility Laboratory, Faculty of Life SciencesUniversity of CopenhagenCopenhagenDenmark
  2. 2.Department of Terrestrial EcologyNational Environmental Research InstituteSilkeborgDenmark
  3. 3.IsoLifeWageningenThe Netherlands
  4. 4.Department of Freshwater EcologyNational Environmental Research InstituteSilkeborgDenmark