Microbiological transformations of soil nitrogen

Nitrogen is one of the most important biogenic compounds. It is indispensable to facilitate growth and functioning of all organisms. This chemical element exist in a soil in many forms and in the soil is very active. Microorganisms play an important role in the nitrogen cycle. The main processes involved in the nitrogen cycle are nitrogen fixation, ammonification, nitrification and denitrification. Nitrogen fixation is the important source of biologically available nitrogen in the biosphere. Ammonification is the reduction of organic compounds to ammonia. Nitrification is a two-step process of oxidation of ammonium to nitrate. Denitrification is the conversion of nitrate to gaseous. The intensity of the microbial processes in soil depend on: type of soil, water content, oxygenation, vegetation, fertilization. Reaction also exert influence on the nitrogen cycle in soil. For most species of microorganisms, the growth is optimal in neutral reaction. In acid soils activity of microorganism and intensity of the processes are inhibited.