78 IRRIGATION. 



C H A P T E K VIII. 



CULTURE OF IRRIGATED GARDEN CROPS. 



There are a few important leading principles involved 

 in the practice of irrigating gardens that should he well 

 considered. These will be referred to in the order of 

 their importance. 



Drainage. It is rarely that a well drained soil can he 

 injured hy a copious supply of water ; hut one that is not 

 drained may easily he turned into a quagmire by an excess 

 of it. Drainage, therefore, should be the first thing pro- 

 vided before this method of cultivation, let it be com- 

 plete or partial only, is attempted. If the soil is not 

 naturally drained by means of an open and porous sub- 

 soil of sand or gravel, tile drains should be laid in such a 

 manner as to carry off the surplus water in the most 

 effective manner. 



The method of drainage will depend upon the system 

 of irrigation adopted. If the bedding plan is used, as 

 illustrated in fig. 7, page 42, the drains should be laid 

 between the beds, and beneath the drain furrows, as 

 shown in fig. 37, in which the open spaces seen at a, a, 

 represent the drain. These drains should be of inch tile, 

 laid three feet below the surface. If laid at a less depth 

 there is danger that the roots of some varieties of plants 

 may penetrate between the crevices and choke the tiles. 

 Where the arrangement of the water-furrows is such as to 

 need change every year, or such as is shown in figures 15, 

 17, or 23, the method of drainage should be the ordinary 

 one of inch tiles laid 24 feet apart, if the soil is heavy ; 

 or 30 feet if of a lighter character, and leading into main 

 drains of two or three inch tile. Surface draining would 

 be a very unsatisfactory resource, and should be adopted 

 only where the crops would resist the effects of a very 



