How can plants and trees take nourishment from the earth?

Question

We always say that energy is a cycle where everything eventually goes back to the earth for plants to pick up. What exactly is it these plants are using as nourishment?

In: Biology

Answer 1

Mostly, what plants take from the soil is nitrogen. This is why farms need to rotate their crops and sometimes plant plants that put nitrogen back *into* the soil, to keep the soil fertile. Presumably they get other trace nutrients from the soil too, like how we need tiny amounts of iron, potasium, etc. Anything they don’t get from the air can only come from the soil, right?