Carbon Sequestration: Do N Inputs and Elevated Atmospheric CO2 Alter Soil Solution Chemistry and Respiratory C Losses? |
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Authors: | P Hill C Marshall H Harmens D L Jones and J Farrar |
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Institution: | (1) School of Biological Sciences, University of Wales, LL57 2UW Bangor, Gwynedd, UK;(2) Centre for Ecology and Hydrology, Deiniol Road, LL57 2UP Bangor, Gwynedd, UK;(3) School of Agricultural and Forest Sciences, University of Wales, LL57 2UW Bangor, Gwynedd, UK |
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Abstract: | 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. |
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Keywords: | climate change dissolved organic carbon elevated CO2 global warming soil organic matter |
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