STORING WATER BY DEEP PLOWING 125 
vation. Moreover, the practice of fallowing should 
be varied with the climatic conditions. In districts 
of low rainfall, 10-15 inches, the land should be clean 
summer-fallowed every other year; under very low 
rainfall perhaps even two out of three years; in 
districts of more abundant rainfall, 15-20 inches, 
perhaps one year out of every three or four is suffi- 
cient. Where the precipitation comes during the 
growing season, as in the Great Plains area, fallowing 
for the storage of water is less important than where 
the major part. of the rainfall comes during the fall 
and winter. However, any system of dry-farming 
that omits fallowing wholly from its practices is 
in danger of failure in dry years. 
Deep plowing for water storage 
It has been attempted in this chapter to demon- 
strate that water falling upon a soil may descend to 
great depths, and may be stored in the soil from year 
to year, subject to the needs of the crop that may be 
planted. By what cultural treatment may this 
downward descent of the water be accelerated by the 
farmer? First and foremost, by plowing at the 
right time and to the right depth. Plowing should 
be done deeply and thoroughly so that the falling 
water may immediately be drawn down to the full 
depth of the loose, spongy, plowed soil, away from 
the action of the sunshine or winds. The moisture 
