What part do (a) nitrifying, (b) nitrogen-fixing and (c) denitrifying bacteria play in the nitrogen cycle?
a) Nitrifying bacteria in the soil change ammonia and other nitrogenous substances (e.g.urea) into nitrates.
b) Nitrogen-fixing bacteria (in the soil or in root nodules) convert gaseous nitrogen into nitrogenous compounds.
c) Denitrifying bacteria in the soil, decompose nitrogenous compounds to make gaseous nitrogen