caa a22 4500 605517754 CHVBK 20210128100721.0 cr unu---uuuuu 210128e20150901xx s 000 0 eng 10.1007/s10533-015-0123-2 doi (NATIONALLICENCE)springer-10.1007/s10533-015-0123-2 Nitrogen addition changes grassland soil organic matter decomposition [Elektronische Daten] [Charlotte Riggs, Sarah Hobbie, Elizabeth Bach, Kirsten Hofmockel, Clare Kazanski] 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 fiveyears. 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. Springer International Publishing Switzerland, 2015 Carbon nationallicence Fertilization nationallicence Microbial respiration nationallicence Soil aggregate nationallicence Nutrient Network nationallicence Wet sieving nationallicence Riggs Charlotte Department of Ecology, Evolution, and Behavior, University of Minnesota, 55108, Saint Paul, MN, USA aut Hobbie Sarah Department of Ecology, Evolution, and Behavior, University of Minnesota, 55108, Saint Paul, MN, USA aut Bach Elizabeth Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 50011, Ames, IA, USA aut Hofmockel Kirsten Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 50011, Ames, IA, USA aut Kazanski Clare Department of Ecology, Evolution, and Behavior, University of Minnesota, 55108, Saint Paul, MN, USA aut Biogeochemistry Springer International Publishing 125/2(2015-09-01), 203-219 0168-2563 125:2<203 2015 125 10533 https://doi.org/10.1007/s10533-015-0123-2 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10533-015-0123-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Riggs Charlotte Department of Ecology, Evolution, and Behavior, University of Minnesota, 55108, Saint Paul, MN, USA aut NATIONALLICENCE 700 1- Hobbie Sarah Department of Ecology, Evolution, and Behavior, University of Minnesota, 55108, Saint Paul, MN, USA aut NATIONALLICENCE 700 1- Bach Elizabeth Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 50011, Ames, IA, USA aut NATIONALLICENCE 700 1- Hofmockel Kirsten Department of Ecology, Evolution, and Organismal Biology, Iowa State University, 50011, Ames, IA, USA aut NATIONALLICENCE 700 1- Kazanski Clare Department of Ecology, Evolution, and Behavior, University of Minnesota, 55108, Saint Paul, MN, USA aut NATIONALLICENCE 773 0- Biogeochemistry Springer International Publishing 125/2(2015-09-01), 203-219 0168-2563 125:2<203 2015 125 10533