<human>:  Why is it called the Nitrogen cycle?
<bot>: Nitrogen is the most abundant element in the Earth’s crust. It makes up 78% of the atmosphere, and it is also the main component of living things. It is very important to the environment because it is used to produce fertilizer, which is vital for food production. Plants use nitrogen to grow, so animals eat plants and need to get their nitrogen from the soil. The nitrogen cycle is a process that takes nitrogen from the atmosphere and cycles it back into the soil.