STORING WATER BY FALL PLOWING 127 
at the right time. In the very great majority of 
cases over the whole dry-farm territory, plowing 
should be done in the fall. There are three reasons 
for this: First, after the crop is harvested, the soil 
should be stirred immediately, so that it can be 
exposed to the full action of the weathering agencies, 
whether the winters be open or closed. If for any 
reason plowing cannot be done early it is often advan- 
tageous to follow the harvester with a disk ard to 
plow later when convenient. The chemical effect on 
the soil resulting from the weathering, made possible 
by fall plowing, as will be shown in Chapter IX, 
is of itself so great as to warrant the teaching .of 
the general practice of fall plowing. Secondly, the 
early stirring of the soil prevents evaporation of the 
moisture in the soil during late summer and the fall. 
Thirdly, in the parts of the dry-farm territory where 
much precipitation occurs in the fall, winter, or early 
spring, fall plowing permits much of this precipita- 
tion to enter the soil and be stored there until 
needed by plants. 
A number of experiment stations have compared 
plowing done in the early fall with plowing done 
late in the fall or in the spring, and with almost 
no exception it has been found that early fall plowing 
is water-conserving and in other ways advantageous. 
It was observed on a Utah dry-farm that the fall- 
plowed land contained, to a depth of 10 feet, 7.47 
acre-inches more water than the adjoining spring- 
