https://hongkong.asiaxpat.com/Utility/GetImage.ashx?ImageID=bd01ece3-e4da-4c6e-9d7b-3d3a47584aa5&refreshStamp=0
Why do we seldom hear about the deteriorating quality of nutrition in our food crops? A recent article, quoting from the US Department of Agriculture (USDA) 2000 food tables, reports that between 1963 and 2000 the nutrient content in all types of fruits and vegetables had declined by up to 50% and continues to decline.
[1] For example, the vitamin C content of peppers dropped from 128 milligrams per 100 grams to 89 milligrams per 100 grams. Broccoli lost half of its vitamin A and calcium, and collards lost much of its magnesium. Cauliflower lost half its vitamin C, thiamine, and riboflavin, and levels of many other nutrients fell as well.
A century ago the magnesium content of our diet was about 500 mg/day, but that has dropped to 175-225 mg/day. Thus, up to 50% of the population in the US and Canada is magnesium-deficient. [2,3]
What happened?
One reason for the deficit is likely that minerals in the soil that crops grew in were lost to the soil once the crops were harvested and left the farm. [4] Further, tilling of the soil often causes erosion of topsoil at a rate (several millimeters per year) that exceeds the rate of natural erosion or creation of topsoil by a factor of ten or more. [5,6]
No-till farming methods that reduce soil erosion rely on herbicides and pesticides, often along with genetically-modified organisms (GMOs), raising havoc with the environment, and killing insects, worms, and soil microbes which are beneficial to a healthy soil ecosystem that nurtures healthy plants. [2] Herbicides such as Glyphosate (RoundUp) bind with magnesium, manganese and other ions, preventing them from being absorbed by plants. [7,8]
http://orthomolecular.org/resources/omns/v16n54.shtml