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 



