title: Different types of nitrogen deposition show variable effects on the soil carbon cycle process of temperate forests.
abstract: Nitrogen (N) deposition significantly affects the soil carbon (C) cycle process of forests. However, the influence of different types of N on it still remained unclear. In this work, ammonium nitrate was selected as an inorganic N (IN) source, while urea and glycine were chosen as organic N (ON) sources. Different ratios of IN to ON (1 : 4, 2 : 3, 3 : 2, 4 : 1, and 5 : 0) were mixed with equal total amounts and then used to fertilize temperate forest soils for 2 years. Results showed that IN deposition inhibited soil C cycle processes, such as soil respiration, soil organic C decomposition, and enzymatic activities, and induced the accumulation of recalcitrant organic C. By contrast, ON deposition promoted these processes. Addition of ON also resulted in accelerated transformation of recalcitrant compounds into labile compounds and increased CO2 efflux. Meanwhile, greater ON deposition may convert C sequestration in forest soils into C source. These results indicated the importance of the IN to ON ratio in controlling the soil C cycle, which can consequently change the ecological effect of N deposition.
authors.affiliation: Hebei College of Industry and Technology, Hongqi Street 626, Shijiazhuang, 050091, China.
authors.forename: Yuhan
authors.initials: Y
authors.lastname: Du
authors.forename: Peng
authors.initials: P
authors.lastname: Guo
authors.forename: Jianqiu
authors.initials: J
authors.lastname: Liu
authors.forename: Chunyu
authors.initials: C
authors.lastname: Wang
authors.forename: Ning
authors.initials: N
authors.lastname: Yang
authors.forename: Zhenxia
authors.initials: Z
authors.lastname: Jiao
mesh_terms: D002244:Carbon / Q000737:chemistry*; D057486:Carbon Cycle; D002681:China; D004798:Enzymes / Q000302:isolation & purification; D065928:Forests; D005998:Glycine / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D014508:Urea / Q000737:chemistry
chemical_list: D004798:Enzymes; D009566:Nitrates; D012987:Soil; D002244:Carbon; D014508:Urea; D009584:Nitrogen; C006568:ammonium nitrate; D005998:Glycine
keywords: carbon cycle; enzymatic activity; forest soil; inorganic nitrogen; litter decomposition; nitrogen deposition; organic nitrogen; soil respiration