Biogeochemistry

, Volume 73, Issue 3, pp 499–513

Denitrification and N2O emission from forested and cultivated alluvial clay soil

Authors

  • Sami Ullah
    • Wetlands Biogeochemistry InstituteLouisiana State University
    • Department of Agronomy and Environmental ManagementLouisiana State University
  • S.P. Faulkner
    • USGS National Wetlands Research Center
Article

DOI: 10.1007/s10533-004-1565-0

Cite this article as:
Ullah, S., Breitenbeck, G. & Faulkner, S. Biogeochemistry (2005) 73: 499. doi:10.1007/s10533-004-1565-0

Abstract.

Restored forested wetlands reduce N loads in surface discharge through plant uptake and denitrification. While removal of reactive N reduces impact on receiving waters, it is unclear whether enhanced denitrification also enhances emissions of the greenhouse gas N2O, thus compromising the water-quality benefits of restoration. This study compares denitrification rates and N2O:N2 emission ratios from Sharkey clay soil in a mature bottomland forest to those from an adjacent cultivated site in the Lower Mississippi Alluvial Valley. Potential denitrification of forested soil was 2.4 times of cultivated soil. Using intact soil cores, denitrification rates of forested soil were 5.2, 6.6 and 2.0 times those of cultivated soil at 70, 85 and 100% water-filled pore space (WFPS), respectively. When NO3 was added, N2O emissions from forested soil were 2.2 times those of cultivated soil at 70% WFPS. At 85 and 100% WFPS, N2O emissions were not significantly different despite much greater denitrification rates in the forested soil because N2O:N2 emission ratios declined more rapidly in forested soil as WFPS increased. These findings suggest that restoration of forested wetlands to reduce NO3 in surface discharge will not contribute significantly to the atmospheric burden of N2O.

Keywords

Bottomland hardwoodDenitrificationGlobal climate changeGreenhouse gasNitrous OxideSharkey soilWetland restoration

Abbreviations

LMV

Lower Mississippi Alluvial Valley

PDA

potential denitrification assay

WFPS

water-filled pore space

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Copyright information

© Springer 2005