STORING WATER IN THE SOIL 111 
16 or 17 per cent. Expressed in another way this 
means that a layer of water from 2 to 3 inches 
deep can be stored in the soil to a depth of 12 
inches. Sandy soils will hold less water than clayey 
ones. It must not be forgotten that in the dry- 
farm region are numerous types of soils, among them 
some consisting chiefly of very fine soil grains and 
which would, consequently, possess field-water 
capacities above the average here stated. The first 
endeavor of the dry-farmer should be to have the 
soil filled to its full field-water capacity before a 
crop is planted. 
Downward movement of soil-moisture 
One of the chief considerations in a discussion of 
the storing of water in’soils is the depth to which 
water may move under ordinary dry-farm conditions. 
In humid regions, where the water table is near the 
surface and where the rainfall is very abundant, 
no question has been raised concerning the possi- 
bility of the descent of water through the soil to the 
standing water. Considerable objection, however, 
has been offered to the doctrine that the rainfall 
of arid districts penetrates the soil to any great 
extent. Numerous writers on the subject intimate 
that the rainfall under dry-farm conditions reaches 
at the best the upper 3 or 4 feet of soil. This 
cannot be true, for the deep rich soils of the arid 
