Profitable cultivation of land under dry-farm conditions is dependent on the efficient use of precipitation. Soil fertility is not at present the limiting factor in crop production on most arid lands, but insufficient moisture to make available the fertility of these dry-lands is not only a limiting factor, but in most cases the controlling factor in crop production. The rainfall in the principal dry-farming areas of Utah varies from 12 to 15 inches a year. During different years it may range from 10 to 22 inches; therefore the best use must be made of the water that falls.
Harris, F. S. and Jones, J. W., "Bulletin No. 158 - Soil Moisture Studies Under Dry-Farming" (1917). UAES Bulletins. Paper 124.