12 BULLETIN 721, U. S. DEPARTMENT OF AGRICULTURE. 
In the irrigated sugar-beet areas usually less than 20 inches of 
moisture falls during the entire year, and frequently many of the 
showers are so light that they are of no practical benefit in crop pro- 
duction. Sugar-beet growers in those sections depend largely upon 
irrigation. Frequently the showers that fall in irrigated areas are 
detrimental rather than helpful in the production of sugar beets, 
since they frequently cause the soil to crust. If this crusting occurs 
shortly after the seed is sown the young plants have great difficulty in 
breaking through to the light, with the result that the stands are 
very seriously injured and replantings are necessary. If the show- 
ers occur soon after the beets are up and the ground crusts around 
the young plants, the air is cut off from the roots and growth is 
interfered with. This may sometimes be remedied by prompt culti- 
vation, although the plants are often so firmly embedded in the crust 
that cultivation is difficult without serious injury to the plants. 
Sometimes a moderately heavy roller of one of the types shown in 
Plate II will produce the desired result in breaking the crust. In 
irrigated sections every effort should be made to retain the fall or 
winter moisture in the soil, and if the ground is dry in the fall, 
irrigation is generally desirable. The soil should be sufficiently 
moist when the seed is planted to produce prompt and complete 
germination, and there should be sufficient moisture in the soil to 
maintain a steady growth for several weeks. As soon as the plants 
indicate that they are suffering from lack of moisture they should 
be irrigated. When beets wilt during the day and fail to revive at 
night they should be watered without delay. Usually from one to 
three irrigations during the growing season are sufficient to produce 
a crop in most of the irrigated sections where sugar beets are grown. 
When beets are irrigated the soil should be thoroughly wet, and every 
effort should then be made to retain the moisture as long as possible 
by frequent cultivation. 
Sunshine. — The third element of climate which has a marked ef- 
fect on the quality of sugar beets is light, over which man has little 
control except in the selection of locality. It is generally believed 
that direct sunshine is an important factor in the production and 
storage of sugar in the beet. Observation indicates, however, that 
diffused light is almost, if not quite, as effective in producing and 
storing sugar as direct sunlight. The importance of light should not 
be overlooked, however, since without it the leaves could not manu- 
facture sugar. Beet sugar is all made in the beet leaves by the action 
of light upon the leaf green when moisture and carbonic-acid gas 
are present. Without light this action in the leaf can not take place, 
no matter how favorable may be all other conditions for growth and 
sugar production. 
