1. Decomposition: After the animal dies, the body begins to decompose. During decomposition, bacteria and microorganisms break down the complex organic compounds in the animal's tissues, including proteins and nucleic acids. This process releases nitrogen in various forms, such as ammonia (NH3) and organic nitrogen compounds.
2. Ammonification: As decomposition continues, the nitrogen-containing compounds released during decomposition undergo further breakdown by microorganisms. This process, known as ammonification, converts organic nitrogen into ammonia.
3. Nitrification: Nitrifying bacteria in the soil or water convert the ammonia produced during ammonification into nitrite (NO2-) and nitrate (NO3-). This process is called nitrification. Nitrite and nitrate are inorganic forms of nitrogen that are essential nutrients for plants.
4. Denitrification: Under certain conditions, denitrifying bacteria convert nitrates into nitrogen gas (N2). Denitrification is an anaerobic process that occurs in waterlogged or oxygen-depleted environments. Nitrogen gas is released into the atmosphere, completing the nitrogen cycle.
5. Plant Absorption: Plants absorb inorganic nitrogen compounds, such as nitrates and ammonium, from the soil and use them for growth and protein synthesis. Animals consume plants or other animals, and the nitrogen becomes incorporated into their tissues.
6. Assimilation and Excretion: Animals assimilate nitrogen into their tissues, particularly in the form of amino acids and proteins. However, animals cannot efficiently use all of the nitrogen they consume. The excess nitrogen is converted into waste products, such as urea or uric acid, and excreted from the body.
7. Return to the Environment: Through decomposition, nitrification, and denitrification, the nitrogen contained in animal remains is eventually returned to the environment. This process completes the nitrogen cycle and ensures the continuous availability of nitrogen for plant growth and other biological processes.
Overall, the nitrogen in an animal after it dies undergoes a series of transformations, including decomposition, ammonification, nitrification, denitrification, and assimilation and excretion. These processes recycle nitrogen back into the environment, where it can be utilized by plants and other organisms, thus sustaining the nitrogen cycle.