There's probably not much erosion going on in a tilled land with 5% organic matter, and organic farmers are the best proponents of cover crops too. It possibly compares with the erosion going on in a no-till field mineralized by decades of chemicals. The author also supports many other techniques, like conservation farming, which he is aware reduces erosion: "We should encourage American farmers to continue these improvements."

Exactly, I said economics, but it's the same thing really, as logistics are driven by demand and profits.

One such way could be to grow more for the local community. Right now, most farmers grow mostly for the industrial or global market, not food for the neighboring cities. If all farmers grew 99% of their acreage as they currently do, and 1%, like 1 small field of potatoes or carrots or lettuce or tomatoes, they would be able to sell them directly to the local grocery stores, and between all farmers around, there would be dozens of different vegetables or fruits or grains or pulse, with probably one more job on the farm.

The problem is not really or not only with more productive crops, but crops (or farm animals) with a greater profit. It is also a problem of marketization, selling transformed products with a higher value, or raw products with a higher premium, like organics, or selling more directly to the consumer, with less intermediaries, is part of the solution. No doubt there are also many other possibilities.