02165nas a2200157   4500008004100000245008800041210006900129300001300198490000700211520161100218100001901829700001701848700001301865700001601878856011301894       2004                        eng d00aCarbon and nitrogen pools in a tallgrass prairie soil under elevated carbon dioxide0 aCarbon and nitrogen pools in a tallgrass prairie soil under elev  a148 -1530 v683 a<p>Soil is a potential C sink and could offset rising atmospheric CO2 The capacity of soils to store and sequester C will depend on the rate of C inputs from plant productivity relative to C exports controlled by microbial decomposition. Our objective was to measure pools of soil C and N to assess the potential for C accrual and changes to N stocks as influenced by elevated atmospheric CO2 Treatments (three replications, randomized complete block design) were ambient CO2&mdash;no chamber (NC), ambient CO2&mdash;chamber (AC), and two times ambient CO2&mdash;chamber (EC). Long-term (290 d) incubations (35&deg;C) were conducted to assess changes in the slow soil fractions of potentially mineralizable C (PMC) and potentially mineralizable N (PMN). Potentially mineralizable C was enhanced (P &lt; 0.1) by 19 and 24% in EC relative to AC and NC soil at the 0- to 5- and 5- to 15-cm depths, respectively. Potentially mineralizable N was significantly greater by 14% at the 0- to 5-cm depth in EC relative to AC, but decreased by 12% in EC relative to NC (P &lt; 0.1). Measurements of PMC indicate that increases in total soil C under elevated CO2 in a previous study were a consequence of accrual into the slow pool. Relatively large amounts of new C deposited as a result of elevated CO2 (Cnew) remained in the soil after the 290-d incubation. In contrast to accumulation of C into the slow fraction, Cnew was integrated into a passive fraction of soil organic matter (SOM). Accumulation of N was also detected in the whole soil, which cannot be explained by current estimates of ecosystem N flux.</p>1 aWilliams, M.A.1 aRice, C., W.1 aOmay, A.1 aOwensby, C.  uhttp://129.130.186.12/content/carbon-and-nitrogen-pools-tallgrass-prairie-soil-under-elevated-carbon-dioxide