<p><strong>Abstract.</strong> Biogas digestate (BD) is increasingly used as organic fertilizer, but has a high potential for NH₃ losses. Its proposed injection into soils as a countermeasure has been suggested to promote the generation of N₂O, leading to a potential trade-off. Furthermore, the effect of high nutrient concentrations on N₂ losses as they may appear after injection of BD into soil has not yet been evaluated. Hence, we performed an incubation

more »

... ent with soil cores in a helium–oxygen atmosphere to examine the influence of soil substrate (loamy sand, clayey silt), water-filled pore space (WFPS; 35, 55, 75<span class="thinspace"></span>%) and application rate (0, 17.6 and 35.2<span class="thinspace"></span>mL BD per soil core, 250<span class="thinspace"></span>cm³) on the emission of N₂O, N₂ and CO₂ after the usage of high loads of BD. To determine the potential capacity for gaseous losses, we applied anaerobic conditions by purging with helium for the last 24<span class="thinspace"></span>h of incubation. Immediate N₂O and N₂ emissions as well as the N₂<span class="thinspace"></span>∕<span class="thinspace"></span>(N₂O+N₂) product ratio depended on soil type and increased with WFPS, indicating a crucial role of soil gas diffusivity for the formation and emission of nitrogenous gases in agricultural soils. However, emissions did not increase with the application rate of BD. This is probably due to an inhibitory effect of the high NH₄⁺ content of BD on nitrification. Our results suggest a larger potential for N₂O formation immediately following BD injection in the fine-textured clayey silt compared to the coarse loamy sand. By contrast, the loamy sand showed a higher potential for N₂ production under anaerobic conditions. Our results suggest that short-term N losses of N₂O and N₂ after injection may be higher than probable losses of NH₃ following surface application of BD.</p>