02224nas a2200157   4500008004100000245013000041210006900171300001300240490000700253520161100260653002201871100001501893700001501908700001701923856012601940       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://knz.lternet.edu/content/changes-enzyme-activities-and-microbial-biomass-tallgrass-prairie-soil-related-burning-and