IRRIGATION REQUIREMENTS OF THE GREAT BASIN 
25 
and otherwise worked an injury. References to results obtained at 
Pullman, Wash., Gooding and Twin Falls, Idaho, although located 
outside the Great Basin, are introduced for the purpose of com- 
parison with those obtained in the Great Basin and because con- 
ditions are somewhat similar. 
FORAGE CROPS 
Alfalfa, clover, and other forage crops differ in certain features 
from the cereals in their water requirements during their several 
stages of growth. As with the cereals, the need for water is small 
in the case of newly seeded alfalfa during the first stage of growth. 
Fig. 13. — Amount of water transpired during growth prior to each of three cuttings 
of alfalfa, as determined at Reno, New, in 1911. Modifying meteorology also 
given. The stepped lines represent mean values for several days 
The demand for water increases, however, quite rapidly as the foliage 
expands, and this increase is accelerated until the root system is w T ell 
established and the aerial part of the plant approaches full develop- 
ment. From this stage to the time of harvesting, the increase in 
water requirement is fairly constant, provided the alfalfa is cut in 
early bloom. If the cutting is deferred to late bloom or beyond, 
there is a falling off in the amount of water needed. Figure 13 js 
a graphical representation of the quantity of water transpired daily 
by alfalfa grown in tanks at Reno, Nev., in 1911. It will be noted 
that it required from April 25 to July 18 (84 days) to mature the 
first crop and during this period the transpiration was low and the 
growth slow. The next crop matured in 35 days and required during 
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