3.2 Priming effect and C substrate mineralization
Glucose amendments had positive cumulative PEs under N and P additions
while negative PE under Control, with the highest PE under P addition
(Figure 2a). Vanillin amendments had negative cumulative PE for all
nutrient treatments, with the highest PE under P addition. The PEs with
glucose amendment were significantly correlated with soil and microbial
C:N, C:P, N:P (Table 1). However, there were no significant
relationships between PEs with vanillin amendment and stoichiometric
characteristics of soil and microorganisms (Table 1).
Compared with control, nutrient additions increased C substrate
mineralization, with much higher mineralization of vanillin than that of
glucose (Figure 2b). Specifically, glucose mineralization was increased
by 45%, 36%, and 33% under N, P and NP addition, respectively (Figure
2b). Vanillin mineralization was increased by 11%, 40%, and 48% under
N, P and NP addition, respectively. Both C substrates (glucose and
vanillin) mineralization was significantly correlated with soil and
microbial C:N, C:P, N:P (except glucose mineralization and soil C:N)
(Table 2).