discussed later, that the amount of water evaporated from the soil
and transpired by plant leaves increases materially with an increase
in the average temperature during the growing season, and is much
higher under a clear sky and in districts where the atmosphere is
dry. Wherever dry-farming is likely to be practiced, a moderately
high temperature, a cloudless sky, and a dry atmosphere are the
prevailing conditions. It appeared probable therefore, that in arid
countries the amount of water required for the production of one
pound of dry matter would be higher than in the humid regions of
Germany and Wisconsin. To secure information on this subject,
Widtsoe and Merrill undertook, in 1900, a series of experiments in
Utah, which were conducted upon the plan of the earlier
experimenters. An average statement of the results of six years'
experimentation is given in the subjoined table, showing the number
of pounds of water required for one pound of dry matter on fertile
soils:--


Wheat 1048
Corn 589
Peas 1118
Sugar Beets 630



These Utah findings support strongly the doctrine that the amount of
water required for the production of each pound of dry matter is
very much larger under arid conditions, as in Utah, than under humid
conditions, as in Germany or Wisconsin. It must be observed,
however, that in all of these experiments the plants were supplied