106 The Sugar-Beet in America 
disk harrow finds occasional use where the land has been 
plowed recently. 
One of the most important reasons for cultivating the 
soil is to conserve moisture. Even in regions of abundant 
rainfall it is often necessary to save soil moisture, and in 
arid regions the very life of agriculture depends on con- 
serving the scant supply of water. If the soil is compact 
and hard, rain water will run off the surface rather than 
penetrate the soil where plants can use it. The soil must, 
therefore, be loosened in order that it may absorb moisture. 
The water that is in the soil moves from particle to particle, 
and if the surface particles are pressed tightly together 
the water will rise to the surface where it is lost by evapora- 
tion. This loss can be prevented by stirring the surface 
and forming a loose, dry mulch of earth which retards 
the escape of moisture. 
TIME OF PLOWING 
Many factors must be considered in determining the 
best time to plow, such as the amount of moisture in the 
soil, the rush of other work, the climatic conditions during 
the winter, the time of harvesting the preceding crop, 
and the time at which the land is to be seeded. As a 
rule, it pays to plow for sugar-beets in the fall rather than 
in the spring. This is probably more true for this crop 
than for any other, although fall-plowing is usually con- 
sidered good for practically all crops; there are, however, 
a few conditions in which spring plowing seems to give 
better results. 
Fall plowing is desirable because it allows the turning 
