CAPILLARY WATER IN THE SOIL 109 
is thoroughly distributed throughout the soil. For 
instance, in sandy soils, the downward descent of 
water is very rapid; in clay soils, where the prepon- 
derance of fine particles makes minute soil pores, there 
is considerable hindrance to the descent of water, 
and it may take weeks or months for equilibrium 
to be established. It is believed that in a dry-farm 
district, where the major part of the precipitation 
comes during winter, the early springtime, before 
the spring rains come, is the best time for determin- 
ing the maximum water capacity of a soil. At that 
season the water-dissipating influences, such as sun- 
shine and high temperature, are at a minimum, and 
a sufficient time has elapsed to permit the rains of 
fall and winter to distribute themselves uniformly 
throughout the soil. In districts of high summer 
precipitation, the late fall after a fallow season will 
probably be the best time for the determination of 
the field-water capacity (Fig. 29). 
Experiments on this subject have been conducted 
at the Utah Station. As a result of several thousand 
trials it was found that, in the spring, a uniform, 
sandy loam soil of true arid properties contained, 
from year to year, an average of nearly 164 per cent 
of water to a depth of 8 feet. This appeared to 
be practically the maximum water capacity of that 
soil under field conditions, and it may be called the 
field capacity of that soil for capillary water. Other 
experiments on dry-farms showed the field capacity 
