Temperature as an environmental factor: Its effect on nitrification

The temperature effects on the nitrification process were studied via enrichment and soil perfusion techniques. Enrichment technique yields optimum data at 30 to 37°C wether the inoculum was soil or soil suspension. Activities of nitrifying microorganisms were observed above 40°C and extended to 50°C in the majority of samples. Direct inoculation of enrichment medium with soil showed satisfactory results for nitrifiers growth rather than the use of soil suspension as inoculum for the same medium. The quantitative study for nitrite formation as an intermediate product in the nitrogen cycle was carried out at 44°C. Nitrite formed by an ammonium oxidizing group was accumulated to high levels at the beginning of percolation. This was followed by a sharp drop, and a gradual decrease was observed afterwards. The rate of nitrification was increased to some extent by using an autoclaved soil sample.