IRRIGATION 121 



are making a steady growth. Two or four applications are 

 usually made during the growing season. The time of these 

 applications is determined by the condition of the plants. 

 Just as soon as they begin to suffer for want of water it is 

 applied. The last application usually comes within four or 

 six weeks before the harvest. This final irrigation is one 

 that requires considerable skill in order that it may be given 

 at the proper time; for if beets are allowed to mature too 

 soon the sugar content will be low. 



Orchard Irrigation. Orchard irrigation is a general 

 practice in certain regions. This no doubt is due to the fact 

 that irrigation represents intensive agriculture and is well 

 suited to the growing of fruits, both large and small, as the 

 value of the crop per acre is generally large. It is customary 

 in irrigation practice for orchards, to keep the moisture con- 

 tent of the soil high enough to insure favorable conditions for 

 the growth of the trees at all times. Methods vary more in 

 orchard irrigation than in any other. In some localities 

 the practice of thoroughly wetting the soil and conserving 

 the moisture by cultivation prevails. Sometimes pipes or 

 similar conduits are used to give a constant supply of water 

 to the soil. Although the last system is not practiced to 

 any extent, it is common to find it in some localities. 



QUESTIONS 



1 . In what three ways does soil moisture leave the soil? 



2. In what kind of soil will moisture losses by seepage be greatest? 



3. Discuss four factors that influence the amount of water required 

 in irrigation. 



4. Why is thorough wetting better than many light applications? 



5. How much water is required for the common crops in the United 

 States, as estimated by Dr. Elwood Meade? 



6. Explain the general methods followed in irrigating grain, 

 alfalfa, potatoes, sugar beets, and orchards. 



