Suppose that instead of having this two-year rotation, that specialize in just corn and beans, we had a three-year rotation, where you have the corn and beans, and then you have a small grain with clover interseeded, and then the clover, of course, is a legume, so it fixes nitrogen in the soil, and then you incorporate that rich, green plant material as a green manure into the soil - all of that begins to feed that living community in the soil that it needs. 