02227nas a2200157   4500008004100000245013000041210006900171300001300240490000700253520161100260653002201871100001501893700001501908700001701923856012901940       1999                        eng d00aChanges in enzyme activities and microbial biomass of tallgrass prairie soil as related to burning and nitrogen fertilization0 aChanges in enzyme activities and microbial biomass of tallgrass   a769 -7770 v313 aMicrobial biomass and enzyme activities are affected by management practices and can be used as sensitive indicators of ecological stability. Microbial biomass C (MBC), microbial biomass N (MBN) and eight enzyme activities involved in the cycling of C, N, P and S were studied in the surface (0–5 cm) of an Irwin silty clay loam soil (fine, mixed, mesic, Pachic Arguistoll) in a tallgrass prairie ecosystem. Treatments of annual spring burning and N fertilization were initiated in 1986 and encompassed: (1) unburned–unfertilized, (2) burned–unfertilized, (3) burned–fertilized, and (4) unburned–fertilized. Activities of dehydrogenase, β-glucosidase, urease, deaminase, denitrifying enzyme, acid phosphatase, alkaline phosphatase, and arylsulfatase were assayed. Long-term burning and N fertilization of the tallgrass prairie soil reduced MBC and MBN relative to the unburned–unfertilized treatment. The effects of burning and N fertilization varied among the enzymes and the time of sampling. Long-term burning significantly (P<0.05) increased activities of urease and acid phosphatase, but decreased activities of β-glucosidase, deaminase and alkaline phosphatase. Long-term N fertilization significantly increased activities of β-glucosidase and acid phosphatase but decreased urease activity. This study found that several soil enzyme activities can be used as indicators of ecological changes caused by N fertilization and long-term burning management practices. The relevance of these changes in surface soil to the long-term sustainability of this ecosystem needs further evaluation.10atallgrass prairie1 aAjwa, H.A.1 aDell, C.J.1 aRice, C., W.  uhttp://lter.konza.ksu.edu/content/changes-enzyme-activities-and-microbial-biomass-tallgrass-prairie-soil-related-burning-and02228nas a2200157   4500008004100000245009100041210006900132300001300201490000700214520165500221653002201876100001501898700001701913700001801930856012201948       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://lter.konza.ksu.edu/content/carbon-and-nitrogen-mineralization-tallgrass-prairie-and-agricultural-soil-profiles