Nitrogen Cycle

Atmospheric or inorganic nitrogen (N2) is converted for use in plants by nitrogen fixation. This process is completed by enzymes in bacteria in root nodules of leguminous plants (such as clover). Consumers eat the organic nitrogen compounds in plants, when these organisms die; they are broken down by saprobiotic microorganisms. Using external egestion, they excrete enzymes to digest organic compounds into ammonia or ammonium ions by ammonification (a reduction reaction). The ammonia is then oxidised by nitrification into nitrites and then nitrates, which can then be directly absorbed and assimilated by plants into useful organic nitrogen containing compound such as amino acids and nucleotides. However this requires nitrifying bacteria and aerobic conditions. In anaerobic conditions, denitrifying bacteria covert nitrate ions into atmospheric nitrogen. This removal of useful nitrate ions can be problematic for farming industry. Waterlogged fields lead to removal of oxygen from soil and thus anaerobic conditions. This can lead to shortage of nitrate ions, lower rate of growth and lower yield of crop and lower productivity and profit Therefore it is imperative that fields be drained at the earliest opportunity. Nitrogen fixing can also occur by lightening and nitrogen fixing bacteria in the soil. These both lead to the production of ammonia.