期刊
EUROPEAN JOURNAL OF SOIL SCIENCE
卷 65, 期 4, 页码 510-519出版社
WILEY
DOI: 10.1111/ejss.12154
关键词
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类别
资金
- National Nature Science Foundation of China [31290222, 31130009, 31070435, 41071166]
- Development Plan Program of State Key Basic Research [2012CB417103, 2010CB833502, 2010CB833501]
- Institute of Geographical Sciences and Natural Resources Research, CAS [2011RC202]
- CAS [XDA05050600]
The effects of atmospheric nitrogen (N) deposition on carbon (C) sequestration in terrestrial ecosystems are controversial. Therefore, it is important to evaluate accurately the effects of applied N levels and forms on the amount and stability of soil organic carbon (SOC) in terrestrial ecosystems. In this study, a multi-form, small-input N addition experiment was conducted at the Haibei Alpine Meadow Ecosystem Research Station from 2007 to 2011. Three N fertilizers, NH4Cl, (NH4)(2)SO4 and KNO3, were applied at four rates: 0, 10, 20 and 40 kg N ha(-1) year(-1). One hundred and eight soil samples were collected at 10-cm intervals to a depth of 30 cm in 2011. Contents and delta C-13 values of bulk SOC were measured, as well as three particle-size fractions: macroparticulate organic C (MacroPOC, > 250 mu m), microparticulate organic C (MicroPOC, 53-250 mu m) and mineral-associated organic C (MAOC, < 53 mu m). The results show that 5 years of N addition changed SOC contents, delta C-13 values of the bulk soils and various particle-size fractions in the surface 10-cm layer, and that they were dependent on the amounts and forms of N application. Ammonium-N addition had more significant effects on SOC content than nitrate-N addition. For the entire soil profile, small additions of N increased SOC stock by 4.5% (0.43 kg C m(-2)), while medium and large inputs of N decreased SOC stock by 5.4% (0.52 kg C m(-2)) and 8.8% (0.85 kg C m(-2)), respectively. The critical load of N deposition appears to be about 20 kg N ha(-1) year(-1). The newly formed C in the small-input N treatment remained mostly in the > 250 mu m soil MacroPOC, and the C lost in the medium or large N treatments was from the > 53 mu m POC fraction. Five years of ammonium-N addition increased significantly the surface soil POC:MAOC ratio and increased the instability of soil organic matter (SOM). These results suggest that exogenous N input within the critical load level will benefit C sequestration in the alpine meadow soils on the Qinghai-Tibetan Plateau over the short term.
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