That's like a perpetual motion machine. Energy is wasted, there is no way around it.
The sun is a great source of free energy.
But not necessarily nutrients/fertilizers and most tractors and transportation today run on ICEs. So it's still not a free lunch.
It needed that fertilizer to grow to even be plowed back in to start. It's just a waste of space for a "good product". It's basically a free pass for next year. No money gained means no profits means profits loss.