"...nutrient content of food since the 1950s which coincides with increased use of chemical fertilizers"

Well, OK, but during the same time, the family farms dissapeared into bigger farms and the Big Agribusiness produced the great majority of the food.

This was done with the support and help of our government. We need enormous amounts of food to conduct our foreign policy. Even Russia knew that they needed to be nice to us in case they had another crop failure and famine.

The quality became less important and crops were devepled for huge yield and pest resistance. Taste and nutrition (per unit) became less important.

The US feeds 20% of the World's people and they must be fed. We are actually working for then, since starving people riot and kill people. Tiger by the tail.