Nitrogen deposition, which is induced by human activities, affects the structure and function of the land ecological system. Researches show that the increase of nitrogen deposition reduces the diversity of the plant species, changes the species composition of the plant community, and increases the productivity of the vegetation. 

Researchers from the Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI) investigated the impacts of nitrogen (N) enrichment on soil physic-chemical property and soil enzyme activities in desert ecosystems, a field experiment by adding N at 0, 1.75, 3.5, 7, or 14g N•m^-2•a^-1 was conducted in a temperate desert steppe in the southeastern fringe of the Tengger Desert. The results showed that N addition led to accumulations of total N, NO₃^—N, NH₄⁺_-N, and available N in the upper soil (0-10 cm) and subsoil (10-20 cm), however, reductions in soil pH were observed, causing soil acidification to some extent. N addition pronouncedly inhibited soil enzyme activities, which were different among N addition levels, soil depths, and years, respectively. Soil enzyme activities were significantly correlated with the soil N level, soil pH, and soil mosture content, respectively. 

This program is financially supported by the Knowledge Innovative Program of The Chinese Academy of Sciences (No.KZCX2-EW-301) and the National Natural Science Foundation of China (No.40930636). The paper has been published on the Chinese Journal of Applied Ecology.