18 BULLETIN '721, U. S. DEPAETMENT OF AGKICULTURB. 



times make serious inroads upon the stand of beets. These pests may 

 be destroyed by the use of poison or by trapping. 



WATER. 



Excess or deficiency of water ijiay be a limiting factor in sugar- 

 beet production. 



Precipitation. — In the humid sections of the sugar-beet area beet 

 growers depend upon rainfall and snow for the necessary supply of 

 soil moisture. Usually the snow and the spring rains put the soil in 

 good condition for planting, and the summer rains keep the crops 

 growing until the end of the season. Whether the precipitation will 

 furnish an excessive amount of moisture for the soil will depend upon 

 soil conditions as well as upon the amount of precipitation. For 

 uniform soil conditions, however, the consideration of precipitation 

 is of vital importance in the growing of sugar beets. Excessive pre- 

 cipitation may be detrimental in two ways: (1) By preventing a 

 proper preparation of the seed bed, and (2) by saturating the soil to 

 such an extent that the air is excluded from the plant roots and the 

 proper growth of the plants thereby prevented. Likewise, a deficiency 

 of precipitation may make a proper preparation of the seed bed impos- 

 sible, or it may put the seed bed in such condition that the germina- 

 tion of the seed or the subsequent growth of the plants may be 

 impaired. Excessive precipitation may be remedied under cer- 

 tain conditions by a proper system of drainage. (See pp. 21-23.) 

 The lack of moisture may be remedied in part (1) by putting the 

 proposed seed bed in a proper condition to catch and hold the 

 fall and winter moisture; (2) by subsequent cultivation, where- 

 by a mulch is formed on the surface of the field, thereby retarding 

 evaporation; and (3) by supplying the soil with a suitable amount 

 of humus. 



Irrigation. — ^The use of irrigating water is theoretically simple, but 

 its practical application is very complex, calling for a knowledge of 

 plant growth and soil requirements based upon experience and good 

 judgment. It is one of the most important factors in sugar-beet 

 production in the semiarid regions. Good crops are sometimes ruined 

 by a lack of knowledge of the water requirements of plants and 

 by want of experience in applying the water. 



There are four sources from which irrigating water may be ob- 

 tained, namely, from reservoirs, direct from streams, from flowing 

 wells, and by pumping. A reservoir is a storage place in which an 

 excess of water due to melting snows or from other sources may be 

 stored for future use. Stream irrigation implies either a continuous 

 or an intermittent flow of water in a river bed which may be drawn 

 upon when needed. Pump irrigation is practicable when the sub- 



