IEEIGATTON REQUIREMENTS OF THE GREAT BASIN 33 
some other standard crop of relatively low water requirements. Ac- 
cordingly it is possible to grade the crops produced in the Great 
Basin into low, medium, and high water requirements. Such crops 
as beans, millet, sorghum, and corn belong to the first named grade ; 
wheat, oats, barley, rye, sugar beets, potatoes, and orchards to the 
second; and the legumes, grasses, rice, and sunflowers to the third 
grade. In localities where water is scarce, it is often f . asible and re- 
munerative for a farmer who practices diversified cropping to raise 
crops of all three grades and thus reduce the average quantity of 
water required for the farm. Under present methods of farming 
in the Great Basin a large percentage of the total irrigated areas 
is devoted to the raising of alfalfa and this practice calls for a liberal 
use of water. Notwithstanding the fact that alfalfa forms the basis 
of most crop rotations and that this product is needed to supplement 
range feed for livestock, it is reasonably certain that in future years 
the percentage of the total irrigated area planted to alfalfa will de- 
crease and that there will be a corresponding increase in the per- 
centage of areas devoted to such crops as peas and other vegetables 
for canning, sugar beets, small fruits, and deciduous orchards. Such 
a change in crops will demand less water and is likely to increase the 
farm profits. 
THE FERTILITY OF THE SOIL 
It is generally true that the richer the soil and the better it is 
tilled the smaller will be the water requirements for any one crop. 
Arid soils are well supplied, as a rule, with mineral plant food, but 
in their uncultivated state they are deficient in decayed vegetable mat- 
ter. Until this deficiency is supplied by crop rotation, the applica- 
tion of manure, and proper treatment of the soil, the water require- 
ment is reasonably certain to be high. To produce heavy yields 
from the use of a given quantity of water, the soil in which the 
crops grow should not only be rich and well tilled but should con- 
tain sufficient vegetable matter derived from manure or the roots 
of legumes to retain the moisture applied in irrigation. The rela- 
tion between the efficiency of irrigation water and the fertility of 
the soil in producing crops is shown in Table 5, which gives the 
yield of each of a number of crops following a leguminous crop or an 
application of manure and the same crop grown on new or less 
fertile land. These experiments formed part of the cooperative irri- 
gation investigations carried on in Idaho during 1910 to 1913 by the 
Bureau of Public Roads and the State Land Board of Idaho. 
WATER REQUIREMENTS AS AFFECTED BY STATE, COMMUNITY, 
AND CORPORATE REGULATIONS 
State legislation and control in the interest of the public welfare, 
decisions of the courts, regulations and methods adopted by com- 
munity enterprises, and water-right contracts entered into between 
irrigation companies and consumers, have all exerted an influence 
upon the quantity of water which can be diverted for definite areas 
of land, in that they have defined the quantity and have attempted 
to make actual practice conform thereto. On the whole it may be 
said that these influences, which in some cases have been'the result 
