20 VEGETABLE GARDENING 



ing 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 pur- 

 pose. Made in this way, reservoirs are very cheap and 

 are easily repaired. It is important to have them large 

 where the supply of water is limited; where the supply is 

 large, the reservoir may be much smaller. Wooden tanks 

 are easily and cheaply constructed for holding water. 



Application of Water Sloping land is necessary 

 for most successful irrigation, if the water is to be applied 

 by the force of gravity. It is difficult to apply water to 

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

 permit the water to flow rapidly over the 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 generally obtained from soils having considerable sand 

 in their composition. 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 evaporation may be saved. 



Cultivate at once after irrigating, if the land will permit 

 of it, so that the soil will not bake. 



Do not apply more than enough water to moisten the 

 land well, and avoid getting it water-soaked. 



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

 vation, for it will not, since without cultivation irrigation is 

 seldom successful. 



