Soils with lower G−/G+ ratios tended to have positive priming effect,
and the extent depended on the pyrolysis temperature of biochar
(Fig. 5). Stronger biochar degradation by gram-positive bacteria might
be accompanied by co-metabolism of SOC, which would therefore
cause the positive priming effect for SOC in acidic soils. Rapid degradation
rate of biochar at lower G−/G+ ratios also indicated the change of
preferential substrate utilization. It was suggested that soil with low
biodegradability SOC and nutrient-poor soils were more likely affected
by priming effects (Blagodatskaya and Kuzyakov, 2008). Since theses
soils were more limited by the availability of energy substrates, the
added substrates would act as an important energy source for microbial
metabolism. Other studies also suggested that the mineralizability of
the SOC determined whether pyrogenic organic matter carbon was a