caa a22 4500 445384301 CHVBK 20180317143027.0 cr unu---uuuuu 170323e20110301xx s 000 0 eng 10.1007/s10021-010-9406-6 doi (NATIONALLICENCE)springer-10.1007/s10021-010-9406-6 Indirect Effects of Nitrogen Amendments on Organic Substrate Quality Increase Enzymatic Activity Driving Decomposition in a Mesic Grassland [Elektronische Daten] [Lisa Tiemann, Sharon Billings] The fate of soil organic carbon (SOC) is determined, in part, by complex interactions between the quality of plant litter inputs, nutrient availability, and the microbial communities that control decomposition rates. This study explores these interactions in a mesic grassland where C and nitrogen (N) availability and plant litter quality have been manipulated using both fertilization and haying for 7years. We measured a suite of soil parameters including inorganic N, extractable organic C and N (EOC and EON), soil moisture, extracellular enzyme activity (EEA), and the isotopic composition of C and N in the microbial biomass and substrate sources. We use these data to determine how the activity of microbial decomposers was influenced by varying levels of substrate C and N quality and quantity and to explore potential mechanisms explaining the fate of enhanced plant biomass inputs with fertilization. Oxidative EEA targeting relatively recalcitrant C pools was not affected by fertilization. EEA linked to the breakdown of relatively labile C rich substrates exhibited no relationship with inorganic N availability but was significantly greater with fertilization and associated increases in substrate quality. These increases in EEA were not related to an increase in microbial biomass C. The ratio of hydrolytic C:N acquisition enzymes and δ13C and δ15N values of microbial biomass relative to bulk soil C and N, or EOC and EON suggest that microbial communities in fertilized plots were relatively C limited, a feature likely driving enhanced microbial efforts to acquire C from labile sources. These data suggest that in mesic grasslands, enhancements in biomass inputs and quality with fertilization can prompt an increase in EEA within the mineral soil profile with no significant increases in microbial biomass. Our work helps elucidate the microbially mediated fate of enhanced biomass inputs that are greater in magnitude than the associated increases in mineral soil organic matter. Springer Science+Business Media, LLC, 2010 grassland nationallicence soil organic carbon nationallicence extracellular enzyme nationallicence microbial biomass δ13C and δ15N nationallicence microbial substrate quality nationallicence decomposition nationallicence Organic matter quality nationallicence Tiemann Lisa Ecology and Evolutionary Biology, University of Kansas, 2101 Constant Ave, Higuchi Hall, 66047, Lawrence, Kansas, USA aut Billings Sharon University of Kansas and Kansas Biological Survey, 2101 Constant Ave, Higuchi Hall, 66047, Lawrence, Kansas, USA aut Ecosystems Springer-Verlag 14/2(2011-03-01), 234-247 1432-9840 14:2<234 2011 14 10021 https://doi.org/10.1007/s10021-010-9406-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10021-010-9406-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Tiemann Lisa Ecology and Evolutionary Biology, University of Kansas, 2101 Constant Ave, Higuchi Hall, 66047, Lawrence, Kansas, USA aut NATIONALLICENCE 700 1- Billings Sharon University of Kansas and Kansas Biological Survey, 2101 Constant Ave, Higuchi Hall, 66047, Lawrence, Kansas, USA aut NATIONALLICENCE 773 0- Ecosystems Springer-Verlag 14/2(2011-03-01), 234-247 1432-9840 14:2<234 2011 14 10021 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer