I call BS. It’s all about the soil, sun, and water. Microbes in the soil are the most important as the help the plants absorb what’s in the soil. Good old compost, manure, ask anyone who gardens.
I didn’t grow up on a farm, but my folks had a feed store. They also had spreader trucks, and custom blended fertilizer for farmers.
My stepfather talked about how most farmers don’t have enough land to let it rest, or plant a crop and plow it in to help the soil.
Some land is just played out.