A field left bare between cash crops loses more than time. Cover crops put living roots back in the ground and pay for themselves in ways that don't show up for a season or two.
Roots hold soil against wind and rain, feed the microbes that cycle nutrients, and break compaction that no tyre pressure can fix. Legume covers even fix their own nitrogen.
Healthy, aggregated soil takes in rain instead of shedding it. Infiltration is a soil-biology story, not just a drainage one.
Markets reward none of this directly — which is why it's worth understanding the economics.