Most of man's food supply comes from the soil, either directly through food crops or indirectly as animal products. The total amount of food produced depends on the fertility of the soil. Many peoples of the world are undernourished because the productivity of the land available is not sufficient to supply the total amount of food needed. A low level of productivity, either absolutely or in terms of the population to be fed, means a lower standard of living. Poverty is often accompanied with malnutrition and disease. In these respects soil conservation and improvement are of great general importance for the promotion of health.
A more direct relationship between soils and health is assumed in the thesis that the nutritional quality of the food supply and particularly of specific foods, apart from the total amount produced, is governed by the fertility level of the soil and is thus influenced by
MAYNARD LA. SOILS AND HEALTH. JAMA. 1950;143(9):807–812. doi:10.1001/jama.1950.82910440004011