Effect of application of sewage sludge compost on the emission of greenhouse gas from soil was investigated by analyzing the dynamic characteristics and emission factor of CO2, CH4 and N2O in soil after spiking two different composts (A:compost with biochar, B:compost without biochar) with varying fertilizing amount into soil. The results indicated that emissions of CO2 and CH4 mainly occurred in the plant growth period with low fertilizer amount of biomass charcoal compost reducing CO2 emissions, and high application content increasing CO2 emissions. CH4 emission fluxes showed negative values, indicating that soil could adsorb CH4, and the adsorbing amount for control was significantly higher than those for other treatments (P<0.01). The absorbing amount in treatment A increased with the fertilizing amount (P<0.05). N2O emissions mainly occurred at the germination and seedling stages, and emission fluxes increased with the fertilizing amount (P<0.01). N2O was considered as the main generated greenhouse gas during agricultural process with sludge compost, and its emission factor from sludge compost soil was 1.02%-1.90% (A compost) and 1.28%-2.93% (B compost), respectively. Biochar could significantly reduce the carbon emission, as the total greenhouse gas released from soil with biochar compost was 19.49% to 35.56% less than that in soil without biochar, which was more obvious for N2O emission reduction (compared with CH4 mitigation).
Keywords: biochar; emission characteristics; greenhouse gas; sludge compost product; soil.