FARM DRAINAGE AND IRRIGATION 221 



between them. If they are further apart, as in orchards, two or more 

 furrows for each row of plants are desirable. The length of furrows will 

 depend on the character of soil. If very porous, they should not be more 

 than 300 feet long. In heavy soils, the length may be as much as 600 

 feet. In this type of irrigation the rows extend at right angles to the 

 ditches, and the water is most conveniently taken from the ditch by dis- 

 tributors previously described. It is usually desirable to turn the water 

 into as many as 50 furrows at one time. 



The Check System. It consists of dividing the field into a number 

 of small compartments, surrounded by low levees. The water is turned 

 in these to the desired depth. This gives a rather complete control of 



CELERY UNDER IRRIGATION, SKINNER SYSTEM. 1 



the amount of water applied to each unit of ground. The size of the 

 checks depends on the slope of the land, small checks being necessary 

 where the slope is severe. This method is adapted to orchard irrigation. 

 Where water is conveyed through pipes and there is sufficient water- 

 head for pipe pressure, spraying irrigation may be resorted to. The 

 Skinner system is probably the most successful of the several spray 

 methods. It consists of a series of pipes at intervals of about forty feet, 

 extending across the field to be irrigated. These are connected with a 

 water main which is closed by a valve when not in use. The lines of pipe 

 are supported at a height of about seven feet on posts, in such a way that 

 the pipes may be turned. The pipes are fitted with small nozzles at 

 intervals of about three feet. These should be in straight lines. The 

 water issuing from them under high pressure is thrown a considerable 



Courtesy of The Pennsylvania Farmer.] ] 



