Full-length sequencing revealed microbial species indicative for growth stage-dependent N2O fluxes in potato cropping on a sandy soil in Germany

Soil microbial communities play a crucial role in agroecosystems, inter alia for the release of nitrous oxide (N₂O). Their structure and hence their functionality is affected by agricultural practices like fertilization as well as by crop growth stages. The aim of this study was to identify potential indicative microbial species which are related to the N₂O formation induced by different N fertilization types (broadcasted or dissolved in irrigation water).

While the general taxonomic composition resembled previously reported microbial community structures in potato cropping, no fertilizer-induced effects, but a time-related clustering of the microbial community structure related to the different development stages of potato plants was found. Out of 5.770 detected species, 64 species were found with a significant positive correlation to the measured N₂O fluxes. In this regard, the family Sphingomonadaceae seem to play a crucial role for the N₂O release while certain species of the genera Altererythrobacter (two out of 26), Novosphingobium (four out of 83), and Sphingomonas (six out of 41) seem to be most indicative. Additionally, four species belonging to the genus Novosphingobium, including the two known species Novosphingobium flavum and Novosphingobium tardaugens as well as five species affiliated to the genus of Rhodanobacter (including Rhodanobacter spathiphylli) might be involved in the process of nitrifier denitrification as recorded by a multifactorial regression model. This might indicate that the assignment of microbial community on genus level (as it has been so far) might overlook the real process involved microorganisms although this knowledge could be helpful for a targeted system control management, particularly in regard to fertilizer application and the real crop's nutrient demand.