Komariah, SitiF, Bernadeta LeniZul, Delita2013-03-042013-03-042013-03-04Rangga Dwijunanda Putrahttp://repository.unri.ac.id:80/handle/123456789/2409Giam Siak Kecil-Bukit Batu Biosphere Reserve (GSK-BB) is one of the peatland ecosystem that most of the regions have been converted into oil palm plantations, industrial forest plantation, and settlement. Environmental conditions disrupted by land conversion will affect the population, diversity and activity of soil microbes. This research aim was to analyze the impact of land use changes to nitrogen fixation bacterial cells number, microbial nitrogen biomass and urease activity in peatlands. Nitrogen fixation bacterial cells number was calculated by using a Total Plate Count (TPC) method, concentration of microbial N biomass was determined by using Chloroform Fumigation Extraction (CFE) and rate of urease activity was determined by quantifying ammonia released during an incubation by adding buffer solution. The result of physical and chemical characteristic of the soil ranged from 3.5 for pH, temperature 28.25-31.25oC, dry weight 21.20-42.86%, water content 63.2- 78.8% and bulk density 0.10-0.34 g/cm3. Cells number of nitrogen fixation symbiotic bacteria ranged from 3⋅2-4⋅9⋅103 CFU/g soil and cells number of nitrogen fixation non- symbiotic bacteria ranged from 3⋅2-9⋅3⋅102 CFU/g soil. Microbial N biomass varied ranging from 1.15-4.29 μg N/g soil and urease activity varied ranging from 3.66-39.28 μg NH4+/g dry weight soil/h. Based on the results obtained, it can be described that the soil quality in the GSK-BB Biosphere Reserve is still capable enough to support the sustainability of soil biological processesotherGSK-BB Biosphere Reserveland usemicrobial N biomassN fixation bacteriasoil ureaseOther