Nitrifier denitrification potentially dominates N2O production in a sandy soil – results from different fertilization and irigation regimes in potato cropping in Germany.

Spatial and temporal distribution of water and nitrogen supply affects soil-borne nitrous oxide (N₂O) emissions. In this study, the effects of different irrigation technologies (no irrigation, sprinkler irrigation and drip irrigation) and nitrogen (N) application types (broadcasted and dissolved in irrigation water) on N₂O emissions and the potentially underlying, genetically determined microbial processes were investigated over an entire season in potato cropping. N₂O fluxes were highest during the first half of the season and mostly affected by the applied water volume rather than the N application types. The comparison of the different water application types revealed that nitrifier denitrification might potentially be the dominant source of N₂O emissions, especially under sprinkler irrigation. The type of N fertilizer supply, broadcasted application or dissolved in irrigation water, showed only minor differences in the potential microbial community functionality. N₂O production in both treatments was most likely also dominated by nitrifier denitrification, while the process of denitrification might be feasible too. Even though the current agronomic management measures generally meet the crop demand of water and N, it might be recommendable to adapt the time of application considering that potatoes mainly require N at later growth stages which could also reduce N₂O emissions at the same time. [ABSTRACT FROM AUTHOR]