Plant biomass, soil chemical properties, and microbial biomass
Aboveground and belowground biomass increased along the N addition
gradient, but the increasing magnitude was higher aboveground than
belowground (Table S1). The N input increase led to an increase in plant
N concentration, soil NH4+-N, and
NO3−-N (Table S2). In contrast, soil
pH significantly decreased by 0.58 units from 7.02 in control (F0) to
6.44 under the highest N addition (F120) level. Soil total C and N
remained stable among treatments.
Fertilization termination led to the quick recovery of aboveground plant
biomass, plant N concentration, and soil pH, as the values were not
significantly different from the control plots (R0).
NO3−-N also remained statistically
unchanged across all treatments after nutrient addition ceased.
NH+4-N content was significantly lower
in previously fertilized soil. Total soil C and N tended to be lower
than control (R0), but statistically insignificant (Table S2). Microbial
biomass N increased after N inputs cessation while microbial biomass C
remained stable (Table S1).