- 1Institute of Soil Research, Department of Ecosystem Management, Climate and Biodiversity, University of Natural Resources and Life Sciences, Vienna, Austria
- 2Centre for Agriculture and the Bioeconomy, Queensland University of Technology, Brisbane, Australia
Sustainable crop production as well as climate change mitigation require a better quantitative process understanding for nitrogen (N) transformations and their response to specific land management strategies. Here we investigated shifts in N transformations following the transition from conventional to soil health-oriented farming using a new combination of 15N stable isotope methods. Soil samples were taken from four different farms in two different regions in Lower Austria following a paired site approach, comparing a clay and a sandy textured soil under conventional vs. organic management. Soils were fertilized with single labelled NH415NO3 and incubated in a fully automated incubation system, with continuous monitoring of 15N2O. Changes in 15N enrichment in N pools were investigated by converting the N pools of interest into NO3-, and further to N2O via the Ti (III) reduction method, establishing the 15N enrichment via cavity ringdown spectroscopy (Picarro G5102-i). Changes in 15N in the NO3- pool showed that gross nitrification was higher in the clay as compared to the sandy textured soil, but did not respond to management. Gross NO3- consumption was however higher in organically managed soils, regardless of texture, and 15N enrichment in the soil microbial biomass indicated negligible assimilation of the applied 15N fertilizer under the conditions of the experiment. Combining classic 15N pool dilution and 15N tracing with Ti (III) reduction and cavity ringdown spectroscopy allowed for a timely determination of N pools and their 15N enrichment, obviating the need for costly and time-consuming analysis via isotope ratio mass spectroscopy. Further tests and analysis are needed to demonstrate the sensitivity of the approach for specific soil N pools, comparing results obtained to isotope ratio mass spectroscopy data. Analysis of the 15N2O data together with the 15N enrichment of the soil N pools will establish the significance of specific pathways of N2O production and their response conventional vs. soil health-oriented farming practices.
How to cite: Hood-Nowotny, R., Bachmann, J., Gallon, S., Breuzeville Calderon, A., Keiblinger, K., and Friedl, J.: Investigating shifts in nitrogen transformations in response to soil health oriented management using a new combination of stable isotope approaches, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21457, https://doi.org/10.5194/egusphere-egu25-21457, 2025.