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

To explore the effects of biochar application on CO and CH emissions as well as the temperature response of CO 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 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 were observed in the BCF treatment, and an increase in CH consumption and reduced competition with NH may be responsible for the significant reduction in CH source strength in biochar-amended soil; and (3) activation energy (E) was identified as an important factor influencing the temperature sensitivity (Q) of CO emissions. Fertilization (CF and BCF) reduced the average Q and E values of CO emissions by 9.0-26.7% and 23.5-10.1%, respectively, relative to the control. In addition, the average E value in the BCF treatment (51.9 kJ mol) was significantly higher than those in the control and CF treatments. The increase in Q and E 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. Our study concludes that biochar amendment increased CO emissions and temperature response of CO emission from the soil-plant system while reducing CH emissions.