The Nitrogen Cycle. The Nitrogen Cycle. Represents one of the most important nutrient cycles found in terrestrial ecosystems. Model that describes the movement of nitrogen in its many forms between the hydrosphere, lithosphere, atmosphere, and biosphere. The Hydrosphere.
The Nitrogen Cycle
The brittle most upper layer of the Earth that is broken up into a number of tectonic plates.
Consists of the heavy oceanic and lighter continental crusts and the upper part of the mantle.
The lithosphere rests on a soft layer called the asthenosphere, over which the plates of the lithosphere glide.
Three processes are responsible for most of the nitrogen fixation in the biosphere are …
atmospheric fixation by lightning
biological fixation by certain microbes - alone or in a symbiotic relationship with plants
Ammonia can be taken up directly by plants - usually through their roots.
Most of the ammonia produced by decay is converted into nitrates. This is accomplished in two steps:
Bacteria of the genus Nitrosomonas oxidize NH3 to nitrites(NO2-).
Bacteria of the genus Nitrobacter oxidize the nitrites to nitrates (NO3-).
Living in the Environment/Eleventh Edition/G Tyler Miller, Jr.