Definition
The nitrogen cycle is the repeating circularization of nitrogen through organic and inorganic materials. Nitrogen changes forms throughout the process and from the atmosphere to the soil to organisms and back again. There are five stages of the nitrogen cycle. Those five stages are: fixation, nitrification, denitrification, decay and putrefaction.
Nitrogen Fixation is the stage in which nitrogen moves from the atmosphere into the soil. Nitrogen in the air is not available for plants and animals to use. This is why Nitrogen Fixation is so important. During this process, bacteria converts Nitrogen into a form that can be used.
Mineralization is the next stage in the nitrogen cycle. This happens when nitrogen moves from organic materials to a form of nitrogen that plants and animals can use. In this stage, microbes act on organic material, such as decomposing plants and animals, and changes the nitrogen into a form that can be used by plants. This stage forms ammonia and ammonium.
Nitrification is the third stage of the nitrogen cycle. During this process, the ammonia form of nitrogen is converted into another form of nitrogen, which are nitrates. Nitrates can be used by plants and they can be used by the animals that eat those plants.
Immobilization happens next in the nitrogen cycle. Microorganisms in the soil also need nitrogen to survive, and during this stage these microorganisms pull nitrogen from the soil. This nitrogen becomes inaccessible to other plants and animals. This stage helps regulate the amount of nitrogen in the soil.
Denitrification is the final stage of the nitrogen cycle, and during this process, nitrogen is returned to the atmosphere, right where we started. And then the whole cycle repeats!