Here Pollan is describing how agroscience has re-enforced the views of the author Sir Albert Howard in recent years:
"As it happens, in the years since Howard wrote, science has provided support for a great many of his unscientific claims: Plants grown in synthetically fertilized soils are less nourishing than ones grown in composted soils; such plants are more productive and less prone to disease than monocultures; and that in fact the health of the soil, plant, animal, human, and even nation are, as Howard claimed, connected along lines we can now begin to draw with empirical confidence. We may not be prepared to act on this knowledge, but we know that civilizations that abuse their soil eventually collapse."*
These various statments are supported by a series of footnotes which includes Asami et al, Tilman, and Diamond to name a few.