Increases in temperature response to CO2 emissions in biochar-amended vegetable field soil

To explore the effects of biochar application on CO 2 and CH 4 emissions as well as the temperature response of CO 2 emissions, a 1-year experiment was conducted with three treatments (control; CF, chemical fertilizer only; BCF, biochar combined with chemical fertilizer) in a vegetable field. The results showed that (1) compared with CF, short-term application of biochar significantly enhanced the cumulative CO 2 emissions by 27.5% from a soil–plant system by increasing the soil microbial biomass (e.g., MBC) and C substrates (e.g., SOC); (2) lowest emissions of CH 4 were observed in the BCF treatment, and an increase in CH 4 consumption and reduced competition with NH 4 + may be responsible for the significant reduction in CH 4 source strength in biochar-amended soil; and (3) activation energy ( E a ) was identified as an important factor influencing the temperature sensitivity ( Q 10 ) of CO 2 emissions. Fertilization (CF and BCF) reduced the average Q 10 and E a values of CO 2 emissions by 9.0–26.7% and 23.5–10.1%, respectively, relative to the control. In addition, the average E a value in the BCF treatment (51.9 kJ mol −1 ) was significantly higher than those in the control and CF treatments. The increase in Q 10 and E a values following biochar application possibly contributed to the supplementation of limited labile C and nutrients but highly resistant C following biochar application. Soil pH and crop cultivation may play key roles in influencing the change in E a . Our study concludes that biochar amendment increased CO 2 emissions and temperature response of CO 2 emission from the soil–plant system while reducing CH 4 emissions.