http://www.soilandhealth.org/01aglibrary/010143albpap/010143idx.html
http://www.soilandhealth.org/01aglibrary/010143albpap/010143csiro.htm
Please scroll 2/3 the way down to read about Kansas wheat and the health of Army recruits from West (arid) and East (more rain) Kansas. Out of respect for the www.soilandhealth.org website I am not posting their images.
Fig. 11. (Continued). Protein concentration in wheat in Kansas, 1949.
Fig. 12. The concentration of dental caries per inductee into the United States Navy 1942 gives a reciprocal curve at that for soil development under the climatic, forces. The minimum of caries is in the Mid-continental area of maximum of soil construction. There is an increase in caries in going westward from there to soils less developed, and more so in going eastward to soils more highly developed.