Michigan Academic Education Standards. The Nitrogen Cycle Process: Nitrogen is taken in by plants through their roots, animals eat plants, and the nitrogen is passed along the food chain to animals. Herbivores get nitrogen by eating plants. Carnivores get nitrogen by eating herbivores. Nitrogen is returned to the soil when an organism dies – decomposers break down the dead organisms and change the nitrogen compounds in the dead organism’s body into the kind plants can use. Read More...