## 5 Conclusions  
We investigated the effect of different maize litter types (young leaves and roots, straw) on CO2, NO, N2O, and N2 emissions under oxic and anoxic conditions in a laboratory incubation study. Addition of maize litter increased litter and SOM derived CO2 emissions, leading to a positive priming effect. SOM priming was highest after addition of maize leaves with a high share of easily degradable C compounds during the first week after onset of incubation. Although litter and SOM turnover were high, NO and N2O fluxes were low under oxic conditions as high O2 diffusivity limited denitrification. The NO/N2O ratio indicated that nitrification contributed to NO and N2O formation during the first two weeks of incubation, especially in Control without litter addition. In the litter-amended treatments, isotopocule mapping revealed that bacterial denitrification dominated N2O formation in the beginning of the incubation experiment with a subsequent shift towards fungal denitrification. With onset of anoxic incubation conditions after 47 days, N fluxes strongly increased and heterotrophic bacterial denitrification became the dominating source of N2O. The N2O/(N2O + N2) ratio decreased with increasing litter C:N ratio and C\({}_{\text{org}}\):NO\({}_{3}\)\({}^{-}\) ratio in soil confirming that the ratio of available C:N is a major control of denitrification product stoichiometry. The following are available online at [[https://www.mdpi.com/article/10.3](https://www.mdpi.com/article/10.3)]([https://www.mdpi.com/article/10.3](https://www.mdpi.com/article/10.3)) 390/app11115309/s1, Figure S1a-c: Solid state \({}^{13}\)C-CPMAS NMR spectra of maize litter used in the incubation experiment, Figure S2: \(\delta^{13}\)C of CO\({}_{2}\) derived from maize litter, Figure S3: Total CO\({}_{2}\) efflux from soil during oxic and anoxic incubation, Figure S4a: \(\delta^{13}\)C of CO\({}_{2}\) evolving from soil and b: fraction of litter-derived CO\({}_{2}\), Figure S5: NO/N\({}_{2}\)O ratio during oxic and anoxic incubation, Figure S6: \(\delta^{18}\)O of N\({}_{2}\)O, added KNO\({}_{3}\), and soil NO\({}_{3}\)\({}^{-}\) at first and last day of incubation, Figure S7a: Fraction of N\({}_{2}\)O originating from heterotrophic bacterial denitrification/nitrifier denitrification and b+c: fraction of residual unreduced N\({}_{2}\)O, Table S1: \(\delta^{15}\)N\({}^{\text{SP}}\)\({}_{\text{N2O}}\), \(\delta^{18}\)O\({}_{\text{N2O/H2O}}\), and \(\delta^{15}\)N\({}^{\text{bulk}}\)\({}_{\text{N2O}}\) endmember values from literature used for isotopocule mapping, Table S2: Cumulative CO\({}_{2}\), NO, N\({}_{2}\)O, and N\({}_{2}\) emissions and denitrification product ratio standardized against litter C input. Conceptualization: P.S.R., R.W., J.P., and K.D., methodology (incubation system): P.S.R., [PERSON], [PERSON]; investigation: [PERSON]; data analysis: [PERSON]; data validation: [PERSON], [PERSON] and [PERSON]; writing--original draft preparation: [PERSON]; writing--review and editing: [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON]; visualization: [PERSON]; supervision: [PERSON], [PERSON], and [PERSON]; funding acquisition: K.D. All authors have read and agreed to the published version of the manuscript. This research work was supported by the Deutsche Forschungsgemeinschaft through the research unit DFG-FOR 2337: Denitrification in Agricultural Soils: Integrated Control and Modelling at Various Scales (DASIM, grant number DI 546/4-1). The APC was funded by the University of Gottingen. Not applicable. The datasets from this study can be found at [[https://doi.org/10.25625](https://doi.org/10.25625)]([https://doi.org/10.25625](https://doi.org/10.25625)) /FKSRMX. We thank [PERSON] and [PERSON] for experimental and laboratory assistance and [PERSON] for soil classification. We acknowledge the Centre for Stable Isotope Research and Analysis of the University of Gottingen for all isotopic analyses, [PERSON] for help with NO analysis, and [PERSON] for \({}^{13}\)C-CPMAS NMR analyses.