Nitrogen addition aggravates microbial carbon limitation: Evidence from ecoenzymatic stoichiometry

Nitrogen (N) deposition may change carbon (C) or nutrient limitation of soil microbes, but whether such change can be reflected by ecoenzymatic stoichiometry has not been well studied. Here, we synthesized data from 36 published studies to evaluate the responses of ecoenzymatic stoichiometry to N addition. Results showed that N addition did not change the enzyme ratio (1:1:1) of C, N, and phosphorus (P) acquisition, and also did not change vector angle of ecoenzymatic stoichiometry which is an indicator of microbial P limitation. However, N addition increased two indicators of C-limitation significantly (i.e., activity of β-D-glucosidase and vector length), both of which indicated that N addition aggravated microbial C-limitation. The aggravated C-limitation may be partly due to the reduced decomposition of recalcitrant organic C. Our study extends our understanding of the effects of N deposition on C cycling from a new perspective.