IRRIGATION OP VINEYARDS. 



91 



irrigation. As a rule irrigation and drainage should go 

 together. Irrigation without drainage will in most cases 

 convert a tract of land into a morass. Stagnant water 

 is fatal to the life of useful vegetation, and it is here that 

 the causes of the failure of many attempts to irrigate 



r 



Fig. 40, PLAN OP IRRIGATING A VINEYARD. 



originate. In arid territories without rainfall, skillful 

 irrigation will supply such a quantity as will be needed 

 to supply evaporation from the surface of the soil and the 

 transpirations of the plants. If more is given, the sur- 

 plus must pass off through the subsoil, or remaining in it 

 will work mischief to the crop. But such an excess of 



a a 



Fig. 41. FURROWS AND DRAINS IN A VINEYARD. 



water can rarely be procured in arid districts. On the 

 contrary, the greatest economy must be exercised in using 

 the limited supply, and waste is impossible. 



It is otherwise in those parts of the country where 

 partial or periodical irrigation is used. There the water 



