90 DRY-FARMING 
the spring and summer is as large or larger some feet 
below the surface than in the upper two feet. The 
tendency of the root is, then, to move downward to 
depths where there is a larger supply of water. 
Especially is this tendency increased by the avail- 
able soil fertility found throughout the whole depth 
of the soil mass. 
It has been argued that in many of the irrigated 
sections the roots do not penetrate the soil to 
great depths. This is true, because by the present 
wasteful methods of irrigation the plant receives so 
much water at such untimely seasons that the roots 
acquire the habit of feeding very near the surface 
where the water is so lavishly applied. This means 
not only that the plant suffers more greatly in times 
of drouth, but that, since the feeding ground of the 
roots is smaller, the crop is likely to be small. 
These deductions as to the depth to which plant 
roots will penetrate the soil in arid regions are fully 
corroborated by experiments and general observa- 
tion. The workers of the Utah Station have repeat- 
edly observed plant roots on dry-farms to a depth 
of ten feet. Lucern roots from thirty to fifty feet 
in length are frequently exposed in the gullies formed 
by the mountain torrents. Roots of trees, similarly, 
go down to great depths. Hilgard observes that 
he has found roots of grapevines at-a depth of 
twenty-two feet below the surface, and quotes Aughey 
as having found roots of the native Shepherdia in 
