Nitrogen Cycle

Nitrogen Cycle

	Nitrogen Cycle Plants, animals and most microbes require combined forms of nitrogen for incorporation into cellular biomass but the ability to fix atmospheric nitrogen is restricted to a limited number of bacteria, archaea, and symbiotic associations.
The bio-geochemical cycling of the element nitrogen is highly dependent on the activities of microorganisms. The positive associations of di-nitrogen fixing bacteria with certain plants provide essential combined nitrogen for crops and ecosystems. One of the most important mutualistic relationships between microorganisms and plants involved the invasion of the roots of suitable host plants by nitrogen fixing bacteria, resulting in the formation of a tumour-like growth called a nodule. Within the nodule the nitrogen fixing bacteria are able to convert atmospheric nitrogen to ammonia, which supplies the nitrogen required for bacterial and plant growth.
Sources of Nitrogen Atmosphere contains about 79%. Soil and rocks contain bound n n-exchangeable ammonia which are released slowly through biological weathering. Inorganic nitrogen ions such as ammonia, nitrites and nitrates occur as salts that are water-soluble and distribute themselves in the soil solution.
Living and dead organic matter also form small, actively cycled reservoirs of nitrogen, e.g. humus. Fertilisers. Volcanic activity, ionising radiation and electrical discharges supply additional combined form of nitrogen to the atmosphere to be added to the soil.