The demand for alfalfa seed has far outrun domestic production. Since the labor and expense of producing the crop are light, and the profits attractive in favorable years, a desire is manifest wherever alfalfa is grown, to save a crop for seed whenever the meteorological elements favor its setting and maturing. Climate is generally acknowledged to be the limiting factor in alfalfa seed production, and the current weather the major factor affecting the yearly yields.
Alter, J. Cecil, "Bulletin No. 171 - Alfalfa Seed Growing and the Weather: With Particular Reference to Conditions in Utah" (1920). UAES Bulletins. Paper 137.