It is generally recognized that shrunken, frosted, or smutty grain is inferior to sound, clean, plump grain. Much has been done on the protein content of grain, and the best millers today purchase grain for its protein content. Few give any consideration to its minerals. Yet do two bushels of sound, plump, clean grain of known protein content grown under the same or different conditions, have the same mineral content? If not, it is of importance to both the producer and consumer: to the consumer because it governs the nutritive value of the product; to the producer because it represents the fertility which is being taken from his soil. Consequently, the value of grain produced on an acre of soil should be measured by the quality as well as the quantity.
Greaves, J. E. and Hirst, C. T., "Bulletin No. 210 - The Mineral Content of Grains" (1929). UAES Bulletins. Paper 166.