Not just a carbon story: uncertainties related to the significance of microbially-produced nitrous oxide during soil carbon sequestration
摘要
In the last decade, in extensive debates on the potential of soil carbon sequestration to decrease the amount of greenhouse gases (GHGs) emitted by soils, and thereby help mitigate climate change, discussions have centred overwhelmingly on CO2. Separate research efforts have shown that other greenhouse gases, and in particular N2O, produced by soil microorganisms, can have a sizeable impact on climate change. At this stage, it is unclear to what extent climate mitigation benefits due to increased soil carbon storage could be offset by N2O emissions from soils. In the present article, we critically review the relevant primary literature. We conclude that reliable data do not exist at this point to determine whether soil carbon sequestration can help mitigate climate change at all. This is in part because of a lack of recognition in past years of the imperative to measure simultaneously all GHG emissions from soils to cope with their large spatial and temporal heterogeneity, and, also because of ignoring the dynamics of the hydric regime of soils. To resolve this question, a comprehensive, interdisciplinary approach of soil organic matter sequestration is needed, encompassing all the factors that can influence the microbial emission of GHGs.