How Does Nitrogen Behave in the Soil?
Once in the soil, all forms of N can undergo a variety of chemical changes. We already discussed how soil microbes can transform N in plant residues or organic soil amendments into plant available N. This process is called mineralization, and the end product is ammonium. Once in the ammonium form, N can be taken up by plant roots. If ammonium is left on the soil surface, it can be lost to the atmosphere as ammonia gas via a process called volatilization. Ammonia is a greenhouse gas that is suspected of contributing to global warming. Ammonium can also be converted to nitrate by soil microbes through a process called nitrification. Like ammonium, soil nitrate can be taken up by plants through the roots. If a soil remains waterlogged for a long period of time and loses its oxygen, nitrate can be converted to a gas by microbes and lost to the atmosphere through a process called denitrification.
