Comparative Effectiveness of Biogas Residue Acidification and Nitrification Inhibitors in Mitigating CO2 and N2O Emissions from Biogas Residue-Amended Soils

Abstract

Owing to their high carbon and nitrogen contents, biogas residues may lead to higher carbon dioxide (CO2) and nitrous oxide (N2O) emissions from soils. Acidification of biogas slurry and application of nitrification inhibitors (NIs) could mitigate the emission of these gases. An incubation experiment was therefore carried out to investigate the effect of NIs, DMPP (3, 4-dimethylpyrazole phosphate), and PIADIN (active ingredients: 3.00–3.25% 1,2,4-triazole and 1.50–1.65% 3-methylpyrazole), on CO2 and N2O emissions from soils fertilized with biogas residues and acidified biogas residues. Biogas residues produced higher ammonium-nitrogen (NH4+-N) and nitrate-nitrogen (NO3−-N) concentrations in soils which resulted in higher emissions of CO2-C and N2O-N than that from acidified biogas residues. Both DMPP and PIADIN significantly decreased the emissions of CO2-C (8.1–55.8%) and N2O-N (87–98%) and maintained lower NH4+-N and NO3−-N concentrations when compared to control (without nitrification inhibitors). However, the DMPP had a higher reduction capability for CO2-C emissions than PIADIN in acidified biogas residue applied soil. In conclusion, the acidification of biogas residues and application of NIs are effect in reducing gaseous emission from biogas residue fertilized soils and thus could improve the fertilizer effectiveness of the residues.