Nitrogen pollution from livestock manure has emerged as an escalating global concern. Hence, it is imperative to assess the farming system that will facilitate the optimal utilization of livestock manure while minimizing environmental impact. In pursuit of sustainable agricultural practices, the implementation of a farming system incorporating crop residues and catch crops has been identified as a promising strategy. Crop residue incorporation is a carbon farming practice that can have significant implications for both soil organic carbon (SOC) and nitrous oxide (N2O) emissions while catch crops have been an important tool for the reduction of nitrogen leaching in the Danish legislation since 1998 (Sommer and Knudsen, 2021).

This study utilizes a process-based model called LandscapeDNDC (Haas et al. 2013) to assess the environmental performances of eight different farming systems in six Danish representative agricultural catchments (LOOPs). Organic fields with major crops in the catchment were fertilized with a mixture of pig and cattle slurry whereas the conventional fields with major crops received mineral fertilizer (sometimes accompanied by a small amount of manure). The + AND – sign in Figure 1 shows the inclusion or exclusion of Catch Crop or Crop Residues in a Conventional or organic field.

The findings in Figure 2 suggest that organic fields lacking crop residue and catch crop exhibit lower N2O emissions per unit area compared to conventional fields with crop residue and catch crop. Specifically, organic fields with winter wheat (WIWH) as the crop show the lowest N2O emissions. Despite this, conventional fields demonstrate higher yields. These results imply that organic farming practices may mitigate nitrogen-related environmental impacts. However, these findings contradict previous studies. Future investigations will explore the underlying reasons for these disparities and reassess the modeling process, potentially incorporating overlooked factors.