Nitrogen addition changes grassland soil organic matter decomposition
Nitrogen addition changes grassland soil organic matter decomposition
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DOI：
10.1007/s10533-015-0123-2
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发表时间：
2015-06
期刊：
影响因子：
4
通讯作者：
C. Riggs;S. Hobbie;E. Bach;K. Hofmockel;Clare E. Kazanski
中科院分区：
文献类型：
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作者：
C. Riggs;S. Hobbie;E. Bach;K. Hofmockel;Clare E. Kazanski
人类在世界范围内显著增加了营养物的沉积和可用性，例如氮（N）。土壤有机质（SOM）是一个重要的全球性碳库（C），然而，这一大的，异质性的C股票的N富集的影响还不清楚。氮的生物，化学和物理因素，确定SOM池的平均停留时间有可变的影响，因此，我们预测，N富集将有不同的影响SOM池，包括池，这是很容易为微生物分解，以及池已稳定对微生物分解通过聚集闭塞和矿物协会。我们解决了这一知识的差距，通过测量N添加在不同的SOM池在美国中部大平原，参加营养网络，并已施肥三年或五年的草地实验的影响。总的来说，氮的添加减少了微生物呼吸的未封闭OM高达29%，相对于对照地块，因此，减少了C损失从这个池。此外，氮添加倾向于增加土壤团聚体和大团聚体中的C包埋。这些结果表明，氮除了将增加碳封存减缓SOM的分解，以及稳定SOM对微生物的分解聚集闭塞池。然而，N对所有池研究的影响各不相同的网站，可能是由于在土壤质地的网站变化。因此，增加固碳土壤中的N富集可能不是普遍的草原。
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.