According to the diagram, how is nitrogen returned to the soil from animals?

Answer 1

This one would be easier with the diagram. But there are only a few ways that I can think of whereby an animal can return nitrogen to the soil.

The first possible method is by excretion. Animals need to "shed" excess nitrogen after breaking down amino acids. As metabolic waste. . So the extra nitrogen is released either by excreting uric acid (birds, reptiles, insects) or urea (as urine) in mammals. Some is also released in fecal matter. This is all potty talk.

That is why people have used manure and night soil as fertilizer for thousands of years; we know it works.

The second method is a bit indirect. When an animal dies, its body decomposes (with some help from the decomposers) and the nitrogen can be returned to the soil this way. Many native peoples plant crops with fish heads added to the soil. It works too.

Does this help?