Data from: Plant-bacteria-soil response to frequency of simulated nitrogen deposition has implications for global ecosystem change

Atmospheric nitrogen (N) deposition, generally, has been simulated through
a single or relatively few N applications per year for its ecological
effect study. Despite the importance of timing in ecosystem processes,
ecological experiments with more realistic N addition frequencies are
rare. We employed a novel design with typical twice (2X) vs. atypical
monthly (12X) N applications per year to explore effects of N addition
frequency on above- and below-ground biodiversity and function. Each year,
several response variables from either belowground or aboveground growth,
N status and cycling, or plant and bacterial diversity differed as a
result of N addition frequency. BNPP showed a large frequency effect in
the relatively moist year but not in the dry year. Nitrogen addition
decreased root growth in the monthly relative to the biannual
applications, which could be highly consequential for predicting changes
in global carbon and nitrogen cycling. Simulated N deposition tended to
perturb biodiversity, but it is noteworthy that 12X applications that
spread N deposition more evenly through a year have much less negative
impacts on plant and bacterial diversities than 2X amendments per year.
Soil N mineralization rate in year 6 was much lower when N additions were
monthly compared with a biannual amendment, especially when simulated N
deposition was high. We have established that amendment frequency matters
for understanding ecosystem response to N deposition. Experiments that
more closely mimic the anthropogenic process of N deposition are needed to
best assess ecosystem and potential global biogeochemical changes.