Study of NOx and CO2 production of cultivated soil in closed microcosm experimental system

The aim of present project was to develop a microcosm experimental method for estimation of NOx and CO2 emission of microbial origin from cultivated soil. The effect of different factors (such as temperature, water supply, mineral-N source and organic matter addition, role of soil organisms and heavy metal contamination) that controlling the accumulation of N2O and CO2 in soil atmosphere and release to air was studied in closed microcosm laboratory model experiments. The headspace gas composition of closed glass vessels of 800–1200 cm3 containing 100–200 g brown forest soil sample was analysed. The N2O and CO2 concentration of gas samples was analysed by gas chromatographic methods and NO-content by means of chemiluminescent detection. Concerning the results, it can be stated that the applied microcosm experimental model proved to be a suitable tool for detecting the effect of factors influencing the NOx and CO2 release from agricultural soil. The temporal changes of N2O and CO2 concentration demonstrated the impact of the coupled microbial processes resulting in these greenhouse gases. The gas production depended on the soil moisture level, temperature and C/N ratio significantly. The inhibitory effect of toxic heavy metals (e.g. Cd) could also be affected by the C/N ratio. The appearance of NO as an intermediate of microbial processes was observed as well.