First results from the ErosioN project

We investigated the effects of soil erosion on the nitrogen cycle as part of a microcosm experiment. Three different stages of erosion induced topsoil dilution with and without plant growth (maize) using ¹⁵N tracing techniques were investigated. This made it possible to track nitrogen transformation processes in the soil. In addition, ¹⁵N labeling enabled the quantification of gaseous nitrogen losses in the form of nitrous oxide (N₂O) and dinitrogen (N₂) using the ¹⁵N gas flux method (¹⁵NGF). The results show that soil erosion reduces gross nitrogen turnover and thus N₂O and N₂ emissions in treatments with and without plants. Plants significantly influenced gaseous nitrogen losses, likely by providing an additional energy source through root exudation at very early growth stages. The oxidation of ammonium to nitrate was by far the dominant nitrogen pathway in all topsoils studied, followed by mineralization and immobilization. Although we observed a trend toward an increase in gaseous losses with increasing erosion, the experiments need to be transferred to the field to understand how nitrogen fluxes change throughout the season.

https://doi.org/10.1016/j.soilbio.2025.109905