IRRIGATION AND ROTATION OP CROPS. 11 



Reservoirs should be on some elevated point. They are 

 easily made by digging out the earth and puddling the bottom 

 and sides with thick clay, which should be at least one foot 

 in thickness and well packed when wet. A good way to pack 

 it is to drive horses over it. When clay cannot be obtained 

 the bottom may be made tight with a thin coating of coal tar and 

 sand, but clay is preferable, and what is known as blue clay is 

 generally best. Cement is liable to crack badly from frost 

 and is not adapted to this purpose. Made in this way, reser- 

 voirs are very cheap and easily repaired. It is important to 

 have them very large where the supply of water is limited; 

 where the supply is large, the reservoir may be much smaller. 



Application of Water. — Sloping land is necessary for most 

 successful irrigation, as it is very difficult to apply water to 

 the surface of level land. The slope should be sufficient to 

 permit the water to flow quickly along its surface and yet not 

 enough to cause it to wash. For irrigation purposes the rows 

 should not be over 300 feet long. The best results are gener- 

 ally obtained from soils having considerable sand in their com- 

 position. Drifting sands may often be made to produce good 

 crops by irrigating and manuring, and lands having some sand 

 in their composition are much better adapted to irrigation than 

 clay soils, since the latter often bake badly or become sticky 

 so that they cannot be cultivated immediately after applying 

 water. 



Rules for Applying Water to Land. — Water should not be 

 applied unless the crop is suffering for it, but the soil should be 

 cultivated thoroughly and frequently, and thus waste by evapo- 

 ration may be saved. 



Cultivate at once after irrigating, if the land will permit 

 of it, so that the soil will not bake; evaporation will thus be 

 prevented, and water will be saved in the soil. 



Do not apply more than enough water to nicely moisten 

 the land and avoid getting it water-soaked. 



Do not think that irrigation will take the place of cultiva- 

 tion, for it will not, since without cultivation irrigation is sel- 

 dom successful. 



Water for irrigating purposes should be somewhat warm 

 when applied. Cold springs do not afford a satisfactory supply 



