Final answer:
The process called ammonification releases nitrogen in the form of ammonium ions during the decomposition of organic material. This is a part of the nitrogen cycle, followed by nitrification and denitrification.
Step-by-step explanation:
The process by which nitrogen is released in the form of ammonium ions (NH4+) during the decomposition of nitrogen-containing organic compounds is known as ammonification. This is a crucial step within the nitrogen cycle, where decomposers like bacteria and fungi break down dead organisms and organic wastes. Following ammonification, the ammonium ions can undergo nitrification, where soil bacteria convert them first to nitrites (NO2−) and then to nitrates (NO3−), which are vital nutrients for plants. Additional processes in the cycle include denitrification, where other bacteria convert nitrates back into nitrogen gas (N2), which is released into the atmosphere.