Data for: Biological mitigation of soil nitrous oxide emissions by plant metabolites

Plant metabolites significantly affect soil nitrogen (N) cycling, but
their influence on nitrous oxide (N2O) emissions has not been
quantitatively analyzed on a global scale. We conduct a comprehensive
meta-analysis of 173 observations from 42 articles to evaluate global
patterns of, and principal factors controlling, N2O emissions in the
presence of root exudates and extracts. Overall, plant metabolites
promoted soil N2O emissions by about 10%. However, the effects of plant
metabolites on N2O emissions from soils varied with experimental
conditions and properties of both metabolites and soils. Primary
metabolites, such as sugars, amino acids, and organic acids, strongly
stimulated soil N2O emissions, by an average of 79%, while secondary
metabolites, such as phenolics, terpenoids, and flavonoids, often
characterised as both biological nitrification inhibitors (BNIs) and
biological denitrification inhibitors (BDIs), reduced soil N2O emissions
by an average of 41%. The emission mitigation effects of BNIs/BDIs were
closely associated with soil texture and pH, increasing with increasing
soil clay content and soil pH on acidic and neutral soils, and with
decreasing soil pH on alkaline soils. We furthermore present soil
incubation experiments that show that three secondary metabolite types act
as BNIs to reduce N2O emissions by 32-45% while three primary metabolite
classes possess a stimulatory effect of 56-63%, confirming the results of
the meta-analysis. Our results highlight the potential role and
application range of specific secondary metabolites in bio-mitigation of
global N2O emissions, and provide new biological parameters for N2O
emission models that should help improve the accuracy of model
predictions.