草原
环境科学
分解
有机质
土壤有机质
氮气
土壤科学
草地生态系统
氮气循环
水文学(农业)
环境化学
土壤水分
农学
生态学
化学
地质学
生物
岩土工程
有机化学
作者
Charlotte E. Riggs,Sarah E. Hobbie,Elizabeth M. Bach,Kirsten S. Hofmockel,Clare E. Kazanski
出处
期刊:Biogeochemistry
[Springer Nature]
日期:2015-06-29
卷期号:125 (2): 203-219
被引量:116
标识
DOI:10.1007/s10533-015-0123-2
摘要
Humans have dramatically increased the deposition and availability of nutrients, such as nitrogen (N), worldwide. Soil organic matter (SOM) is a significant global reservoir of carbon (C); however, the effects of N enrichment on this large, heterogeneous C stock are unclear. Nitrogen has variable effects on the biological, chemical, and physical factors that determine SOM pool mean residence time; consequently, we predicted that N enrichment would have distinct effects on SOM pools, including the pool that is readily available for microbial decomposition, as well as the pools that have been stabilized against microbial decomposition via aggregate occlusion and mineral association. We addressed this gap in knowledge by measuring the effects of N addition on different SOM pools at five grassland experiments in the US Central Great Plains that participate in the Nutrient Network and have been fertilized for three or five years. Overall, N addition decreased microbial respiration of unoccluded OM by as much as 29 % relative to control plots, and consequently, decreased C loss from this pool. Furthermore, N addition tended to increase soil aggregation and C occlusion in large macro-aggregates. These results suggest that N addition will increase C sequestration by slowing the decomposition of SOM, as well as stabilizing SOM against microbial decomposition in aggregate-occluded pools. However, the effects of N on all pools studied varied among sites, possibly due to site variation in soil texture. Consequently, increased sequestration of soil C in response to N enrichment may not be universal across grasslands.
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