Long-Term Impact of Biogas Production on Soil Organic Carbon Storage
Nadia Prays, Uwe Franko

Biogas residue (BGR) is a by-product of a biogas production, which is used as organic fertilizer in agriculture. We hypothesized that replacing undigested organic fertilizers with BGR leads to a decrease in soil organic carbon (SOC) due to (1) carbon off take during the anaerobic digestion process and (2) the change in cropping system after biogas production is implemented. Nine fields that were amended with BG Rs were selected to study carbon fluxes using the CANDY (CArbon and Nitrogen Dynamics) model. Two scenarios were analyzed. First, a simulation from 1973 to 2050 with a repeat of the cropping system and a crop rotation were used to evaluate the impact of BGR on soil. In the second scenario the BGR application was replaced with undigested cattle slurry using the same amount of N (kgNha-1). Additionally, the cropping system from 1973 to 2016 was analyzed to highlight the most important drivers of SOC accumulation. The results demonstrated that BGRs did not affect SOC negatively over a period of ten years. The simulation predicted similar effect of BGRs and cattle slurry on SOC. The analysis of the cropping system showed that the changes in cropping system had greater impact on SOC than fertilization.

Full Text: PDF     DOI: 10.15640/jaes.v7n2a2