Mineralisation of carbon and plant uptake of phosphorus from microbially-derived organic matter in response to 19 years simulated nitrogen deposition

Ully H. Kritzler, David Johnson

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Here we test the hypotheses that 19 years of simulated pollutant N deposition increases both losses of carbon (C) and the ability of plants to access P from organic material in upland heathland. The grass, Dactylis glomerata, and the dwarf shrub, Calluna vulgaris, were grown in soil containing microbial-derived organic matter labelled with C-14 and P-33. We found that both soil and root-surface phosphatase activity increased significantly in response to N deposition. We also found a significant positive relationship between root-surface phosphatase activity and P-33 uptake for Calluna, but a negative relationship for Dactylis. Efflux of C-14 from the microbial-derived organic matter was strongly dependent on an interaction among plant presence, plant species and N deposition. Our results show that mineralisation of C and P, and subsequent plant uptake of P from organic sources is decoupled. In our experimental conditions, stimulation of P turnover coupled with subsequent plant uptake through up-regulation of root phosphatases is little affected by N addition. However, our data indicate that root-surface phosphatases are likely to be more important for uptake of P derived from organic sources for Calluna than for Dactylis.

Original languageEnglish
Pages (from-to)311-319
Number of pages9
JournalPlant and Soil
Issue number1-2
Publication statusPublished - Jan 2010


  • phosphatase
  • nitrogen deposition
  • heathland
  • carbon mineralisation
  • organic phosphorus
  • P-33
  • C-14
  • starvation inducible metabolism
  • surface phosphatase-activities
  • fungus hymenoscyphus ericae
  • P-31 NMR-spectroscopy
  • lycopersicon-esculentum
  • acid-phosphatase
  • soil microbes
  • biomass
  • grasslands
  • decomposition

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