The nitrogen cycle involves three major steps: nitrogen fixation, nitrification, and denitrification. The nitrogen-fixing bacteria convert nitrogen in the soil to ammonia, which is taken up by plants. After nitrogen has been fixed, other bacteria convert it into nitrate, in a process known as nitrification. In the first step of this process, Nitrosomonas convert ammonia into nitrite, and in the second step, nitrite is converted into nitrate, by Nitrobacter. This nitrate is then consumed by plants.The final aspect of the nitrogen cycle is the process of denitrification. This process is performed by a variety of microscopic bacteria, fungi, and other organsims. Nitrates in the soil are broken down by these organsisms, and nitrogen is released into the atmosphere.