Measuring ecosystem functions; denitrification enzyme assay in Mara wetland, Tanzania

Mara wetland in Tanzania is the source of livelihood for people living around the wetland. However this wetland is now under stress from the land use changes along the Mara River basin.The aim of this study was to quantify the potential denitrification rates along the cross-section of wetland and determination of limiting factors for denitrification in different hydrogeomorphological units (HGMUs). Other factors effecting potential denitrification were also reported. Study area was divided into three different HGMUs namely permanently flooded, temporarily flooded and agriculture/grazing area.Acetylene inhibition method was used for denitrification enzyme assay in soil samples from the different HGMUs. Agriculture/grazing HGMU have the lowest potential denitrification rate 0.03 (± 0.22)μg N2O/g DW/hour. The highest potential denitrification rate was 3.08 μg N2O/g DW/hour in permanently flooded HGMU. However variability in rates of potential denitrification rate was very high because of technical limitation in all the methods to measure denitrification rates.