Water, Air, & Soil Pollution: Focus

, Volume 4, Issue 6, pp 177-186

First online:

Carbon sequestration: Do N inputs and elevated atmospheric CO2 alter soil solution chemistry and respiratory C losses?

  • P. HillAffiliated withSchool of Biological Sciences, University of Wales Email author 
  • , C. MarshallAffiliated withSchool of Biological Sciences, University of Wales
  • , H. HarmensAffiliated withCentre for Ecology and Hydrology
  • , D. L. JonesAffiliated withSchool of Agricultural and Forest Sciences, University of Wales
  • , J. FarrarAffiliated withSchool of Biological Sciences, University of Wales

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Soil respiration is a large C flux which is of primary importance in determining C sequestration. Here we ask how it is altered by atmospheric CO2 concentration and N additions. Swards of Lolium perenne L. were grown in a Eutric cambisol under controlled conditions with and without the addition of 200 kg NO 3 −N ha−1, at either 350 ppm or 700 ppm CO2, for 3 months. Soil respiration and net canopy photosynthesis were both increased by added N and elevated CO2, but soil respiration increased proportionately less than fixation by photosynthesis. Thus, both elevated CO2 and N appeared to increase potential C sequestration, although adding N at elevated CO2 reduced the C sequestered as a proportion of that fixed relative to elevated CO2 alone. Across all treatments below-ground respiratory C losses were predicted by root biomass, but not by soil solution C and N concentrations. Specific root-dependent respiration was increased by elevated CO2, such that belowg-round respiration per unit biomass and per unit plant N was increased.


climate change dissolved organic carbon elevated CO2 global warming soil organic matter