Abstract: This research studied the general response to nitrogen deposition, of soil N fractions, grassland C∶N∶P stoichiometry and microbial respiration. Data from 92 published articles from within China and abroad were analyzed by meta-analysis and the effects of nitrogen deposition rate, experimental duration and climatic conditions on nitrogen behavior were studied. It was found that, nitrogen deposition significantly increased soil total nitrogen (7.1%), available nitrogen (36.3%), ammonium nitrogen (51.3%), nitrate nitrogen (98.1%) and microbial biomass C∶P (53.6%), and significantly decreased soil pH (-5.9%), microbial biomass nitrogen (-11.5%), and microbial biomass phosphorus (-19.4%). With increase in nitrogen deposition rate, increases were seen in the size of the effect on total nitrogen (4.1%), soil N∶P (10.6%), dissolved organic nitrogen (41.8%), ammonium nitrogen (31.3%) and nitrate nitrogen (20.8%), while decreases were seen in soil pH (-5.8%), microbial biomass carbon (-13.2%), microbial biomass nitrogen (-11.5%), microbial biomass phosphorus (-18.0%), microbial biomass C∶P (-26.5%) and microbial respiration (-10.6%). As the experimental duration increased, the size of the nitrogen deposition effect on soil ammonium nitrogen (22.8%) significantly increased, while the effect on soil pH (-2.5%), microbial biomass carbon (-12.2%), microbial biomass nitrogen (-21.4%), and microbial respiration (-25.3%) significantly decreased. In addition, the mean annual temperature and precipitation significantly affected the response of microbial respiration to nitrogen deposition, but had no effect on the response of soil and microbial carbon, nitrogen and phosphorus to nitrogen deposition.

Key words: nitrogen deposition, grassland, C:N:P stoichiometry, meta-analysis