266 



SOIL PHYSICS AND MANAGEMENT 



Returns from Sugar Beets Where 80 Acre-Inches are Distributed Over Different 



Areas * 



From the above table it will be seen that 30 acre-inches spread 

 over three acres gives the greatest net returns. The results of the 

 Utah Station indicate that where the annual rainfall is 12 to 15 

 inches an application of 10 to 20 inches is sufficient for ordinary 

 crops, and the best amount lies near the lesser quantity. Dr. F. II. 

 Newell is of the opinion that 12 acre-inches is sufficient to produce 

 good crops of all kinds except alfalfa and a few other similar crops. 



Loss of Water from Canals. It is everywhere agreed that a 

 very large part of the water diverted from streams is lost before it 

 reaches the place where it is to be applied to the land. It is esti- 

 mated that 5.77 per cent of the water is lost for each mile of canal 

 through which it is carried. This means that all the water would 

 be lost in 17 miles. The loss is caused by evaporation and seepage. 

 The canals pass over all kinds of soil, both porous and impervious. 

 Large amounts are lost where the canal passes over gravelly or 

 sandy soil. This seepage water not only does very little good, but 

 in many cases does much harm by causing the water table to rise 

 injuriously near the surface and also brings up the alkali. Some 

 expedients are used to diminish this loss. The soil is sometimes 

 puddled by dragging chains in the bottom of the canals (Fig. 119), 

 thus rendering the soil less pervious. The bottom and sides of 

 canals are sometimes covered with crude oil to lessen leakage. The 

 large canals are sometimes lined with concrete (Fig. 114), which 

 limits the loss to the evaporation. Even fine soil constituents, such 

 as clay or silt, have been used for lining the canals to render them 

 less pervious. This is accomplished in part by the sediment carried 

 by water. 



It is estimated that in India the loss is from 20 to 75 per cent 

 from the canals. The investigations of the Department of Agri- 

 culture in this country show that nearly GO per cent of the water is 

 lost between the head gates and the laterals and a considerable por- 

 tion of the remaining 40 per cent is lost before it reaches the land 



