Responses of soil respiration and C sequestration efficiency to biochar amendment in maize field of Northeast China

Abstract

The application of biochar in agricultural ecosystems is a viable strategy for mitigating climate change and ensuring food security. Northeast China is China’s main maize-growing region, as well as the country's greatest commodity grain base. However, due to a lack of long-term field investigations, information on the effects of biochar on soil CO2 emissions and C sequestration in brown soil in Northeast China is restricted. A 3-year field experiment was conducted in Northeast China with biochar applied at 0 (CK), 15.75 (BC1), 31.5 (BC2), and 47.25 (BC3) t ha−1 rates to explore the continuous impacts on soil CO2 emissions, soil enzyme activities, humic substance (HS) composition, and C sequestration efficiency (CSE). The soil CO2-C emissions in biochar treatments were significantly higher (18.04–73.15 %) than in the control during the maize-growing season. Biochar amendment induced a significant increase in soil urease, sucrase, catalase, and β-glucosidase activities and a significant decrease in bulk density (BD). Furthermore, significant positive correlations were observed between soil CO2 emissions and the four enzymes mentioned above. The C content of humin (HU) increased dramatically as the rate of biochar use increased, whereas the C content of humic acid (HA) and fulvic acid (FA) remained unchanged. The soil C storage levels in the 0–60 cm soil depth in BC1, BC2, and BC3 were 13.30 %, 24.41 %, and 39.06 % higher than CK. The CSE ranged from 80.4 % to 87.6 %, depending on biochar addition rates. To conclude, the present study suggested that maize stover biochar incorporation had a great potential for improving soil C sequestration to agricultural soils of Northeast China, even though biochar addition enhanced soil respiration and enzyme activities.