title: Enhancement of carbon sequestration in soil in the temperature grasslands of northern China by addition of nitrogen and phosphorus.
abstract: Increased nitrogen (N) deposition is common worldwide. Questions of where, how, and if reactive N-input influences soil carbon (C) sequestration in terrestrial ecosystems are of great concern. To explore the potential for soil C sequestration in steppe region under N and phosphorus (P) addition, we conducted a field experiment between 2006 and 2012 in the temperate grasslands of northern China. The experiment examined 6 levels of N (0-56 g N m(-2) yr(-1)), 6 levels of P (0-12.4 g P m(-2) yr(-1)), and a control scenario. Our results showed that addition of both N and P enhanced soil total C storage in grasslands due to significant increases of C input from litter and roots. Compared with control plots, soil organic carbon (SOC) in the 0-100 cm soil layer varied quadratically, from 156.8 to 1352.9 g C m(-2) with N addition gradient (R(2) = 0.99, P < 0.001); and logarithmically, from 293.6 to 788.6 g C m(-2) with P addition gradient (R(2) = 0.56, P = 0.087). Soil inorganic carbon (SIC) decreased quadratically with N addition. The net C sequestration on grassland (including plant, roots, SIC, and SOC) increased linearly from -128.6 to 729.0 g C m(-2) under N addition (R(2) = 0.72, P = 0.023); and increased logarithmically, from 248.5 to 698 g C m(-2)under P addition (R(2) = 0.82, P = 0.014). Our study implies that N addition has complex effects on soil carbon dynamics, and future studies of soil C sequestration on grasslands should include evaluations of both SOC and SIC under various scenarios.
authors.affiliation: Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing, China.
authors.forename: Nianpeng
authors.initials: N
authors.lastname: He
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yu
authors.forename: Ruomeng
authors.initials: R
authors.lastname: Wang
authors.forename: Yunhai
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yang
authors.initials: Y
authors.lastname: Gao
authors.forename: Guirui
authors.initials: G
authors.lastname: Yu
mesh_terms: D057965:Carbon Sequestration; D002681:China; D009584:Nitrogen / Q000737:chemistry* / Q000378:metabolism; D010758:Phosphorus / Q000737:chemistry* / Q000378:metabolism; D006109:Poaceae / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D013696:Temperature
chemical_list: D012987:Soil; D010758:Phosphorus; D009584:Nitrogen