02225nas a2200157   4500008004100000245009100041210006900132300001300201490000700214520165500221653002201876100001501898700001701913700001801930856011901948       1998                        eng d00aCarbon and nitrogen mineralization in tallgrass prairie and agricultural soil profiles0 aCarbon and nitrogen mineralization in tallgrass prairie and agri  a942 -9510 v623 aIn situ mineralization of N may contribute significantly to total inorganic-N pools deep in the soil profile. We conducted long-term laboratory incubation experiments to evaluate the net C and N mineralization in soils collected from various depths in tallgrass prairie and agricultural fields of the same geological materials and soil type. Samples were packed to a bulk density of 1.4 g cm-3 in 5-cm-diameter by 10-cm-long cores. The cores were incubated at 35°C for 40 wk in sealed containers. Net C mineralization was measured by evolved CO2, and N mineralized was measured by periodic leaching with NH+4 and NO-3 measured in the leachate. Carbon and N mineralization in the surface horizon were greater in the tallgrass prairie than in the agricultural soil. In both the tallgrass prairie and agricultural soil profiles, C mineralization was least at the water-table depth. Carbon mineralization was described by a first-order kinetic model, but N mineralization was described better by a consecutive (sigmoidal) reaction model. At most depths, the ratios of potentially mineralizable organic C (C0) to total organic C (C0/TOC) and potentially mineralizable organic N (N0) to total N (N0/TN) were greater in the agricultural soil profile than in the tallgrass prairie soil profile. The C0 and N0 in the surface soil (0–0.2 m) represented 11.6 and 12.2% of the total organic C and N pools for the tallgrass prairie soil profile, respectively, and 21.0 and 10.2% of the total organic C and N pools for the agricultural soil profile. Management practices affected the mineralization potentials and rates of both the surface and subsurface soils.10atallgrass prairie1 aAjwa, H.A.1 aRice, C., W.1 aSotomayor, D.  uhttp://knz.lternet.edu/content/carbon-and-nitrogen-mineralization-tallgrass-prairie-and-agricultural-soil-profiles