One of the goals of regenerative agriculture is to get most of the benefits of fallow land while still using the land.
From that standpoint, the math about "but you get less yield" is a bit of a non sequitur. I'm changing the divisor in the equation, which is usually how bad logic slips into an argument predicated on numbers.
Crops on the field are not yet the harvest; grain in a granary is. Harvesting is a very intense process, because the crops need to be collected in the few days when they are best quality and haven't fallen off. Harvesting often occurs around the clock in the season, using monstrous machines.
The lower the yield per unit area, the longer it takes to harvest all, the more fuel is spent, and the higher the risk to lose a part of the crops due to harvesting them untimely. Lower-density crops are noticeably more expensive as a result.
We are collecting and redistributing grain at a discount and using it for anything we can think of. Highly processed food, grain alcohol, “corn fed beef” which is likely a dietary disaster for humans.
Remember, ethanol in gasoline is predominantly about lifting demand for corn in order to court votes from the upper Midwest. We don’t actually need to use corn for fuel.
You can feed pigs on grain and nuts that fell before or after harvest. Ten pigs are pretty big harvesting machine. Birds as well.
Mark Shepard is claiming about twice the yield per acre of conventional farms. He’s doing this by getting less than half a yield of four+ crops on the same land. The trick to being Mark Shepard is putting enough time and energy into your job to understand a dozen crops instead of hyper specializing in two, as if your neighbors aren’t doing the exact some thing.
Now at the end of the day, we still need some staple crops around. That we can stockpile grain for three years and canned food for 18-36 months helps level out boom and bust cycles in agriculture. Good year? Rent warehouse space. Bad year? Let the warehouse lapse, or do invasive maintenance.
Regenerative agriculture is still a big step down from returning the land to natural ecosystems. Quantifying how big that step is, to the point of being able to pick a point in the pareto curve, is a big political decision. There's definitely a place for a lot lots of regenerative agriculture, but it's one part of a solution.
We must have this high leve of productivity before it's even a possibility, but once it's a possibility we can expand its use.
The current economic system is changeable, one ag technology allows us to.