Different natural processes such as nutrient uptake by plants and chemical reactions like nitrification and denitrification discriminate against heavy isotopes such as the naturally abundant  ¹⁵N  or ¹³C (Denk et al., 2017). Agricultural fields can further differ in their respective ratios of abundant isotopologues depending on the treatment and fertilization (Desrochers et al., 2022).

Analyzing isotopic ratios can therefore be a useful tool to investigate nitrogen and carbon sinks, sources and processes.

Field set-up: the long-term experimental field CRUCIAL contains 40 plots on which various treatments have been applied throughout the last 20 years.

Fertilizer/treatment, soil and grain samples are stored, and their carbon and nitrogen isotopes can be analyzed via mass spectrometry. Temporal patterns as well as the influence of respective fertilization treatments will be investigated and visually presented in maps: so-called isoscapes.

The project aims to improve the inferences on which processes dominate the isotopic ratios of N and C and whether the impact of treatments differs significantly.