related to the duration and amount of N added to an
ecosystem , with
reductions in soil respiration regardless of the form of
N added . Likewise, microbial
enzyme activities can be highly sensitive to increases in
N, especially those enzymes that degrade complex C
compounds . Further, Craine et al. (2007) found that N additions
decrease recalcitrant-C mineralization, causing an
overall decline in soil decomposition rates. This commonly
observed suppression of microbial activity
under N enrichment could be considered somewhat
counterintuitive given that plant productivity generally
increases with addition of N , which
would likely increase C inputs to soils