N2O emissions as response of process-related soil microbial activity to different irrigation and nitrogen fertilization regimes in potato cropping
Final Report Abstract
Nitrous oxide (N2O) is one of the most important greenhouse gases emitted nowadays. Soilborn N2O emissions are based on microbial processes which are affected by agronomic measures. Irrigation and nitrogen (N) fertiliser application support an efficient crop production, but simultaneously stimulate microbial mediated N2O production. Therefore, this project investigated the effects of different irrigation systems (no irrigation, sprinkler irrigation or drip irrigation) and N application types (broadcasted or dissolved in irrigation water) on the N2O flux rates over three years in a potato cropping system. Microbial analysis combining microbial biomasses with the quantification of functional genes related to the N cycle were carried out to assess the potential processes of N2O formation. In the first season, N2O fluxes were mainly explained by changes in the soil temperature, while N2O was most probably the result of either denitrification or a by-product of nitrification. Higher microbial biomass was found in the top soil layer, while the bacterial biomass dominated over the fungal biomass. The correlation pattern between the bacterial biomasses and the investigated genes as well as among the functional genes indicated a more diverse potential of N2O production in plots which received several small N doses in irrigation water. However, the overall N2O flux rates remained unaffected. In the second season, N2O fluxes were mostly affected by the applied water volume and less by the N application types. Moreover, highest N2O flux rates occurred during the first half of the season, while the nitrifer denitrification was most probably the underlying pathway of N2O formation. Unexpectedly, the simultaneous application of water and N in several small doses under fertigation did neither lead to a significant increase in crops yields nor to a reduction of N2O emissions. In conclusion, the current agronomic management measurers seemingly lead to an oversupply of water and nutrients and hence higher N2O emissions. This emphasises the need of a more demand-based application considering the real nutrient uptake during the crop growth stages to ensure efficient crop yields while simultaneously mitigate negative environmental impacts such as N2O emissions.
Publications
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Effects of irrigation and fertilization practice on soil nematode communities in arable land. Applied Soil Ecology, 177, 104546.
Ewald, Martin; Rusch, Daniel; Rißmann, Cornelia; Trost, Benjamin; Theuerl, Susanne & Ruess, Liliane
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„International conference on Zero Greenhouse Gas Emission in High Productive Agriculture“, Denmark (3rd-5th of May 2022)
Storch LC; Schulz K.; Rißmann C.; Prochnow A.; Rueß L.; Trost B. & Theuerl S.
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Nitrogen fertilization and irrigation types do not affect the overall N2O production potential of a sandy soil, but the microbial community structure and the quantity of functional genes related to the N cycle. Applied Soil Ecology, 192, 105083.
Storch, Laura Charlotte; Schulz, Katharina; Rißmann, Cornelia; Cerull, Eduardo; Plakias, Alexander; Schlichting, Iris; Prochnow, Annette; Ruess, Liliane; Trost, Benjamin & Theuerl, Susanne
