356 Irrigation and Drainage 



rods long and, from a single head ditch, sending the 

 water the whole length. They were nominally using 

 175 Colorado inches of water, distributing it in alter- 

 nate furrows. 



Before going home at night they divided this head 

 between 40 rows which had been once irrigated, 



Fig. 94. Irrigating potato rows 40 rods long from head ditch of Fig. 92. 



gauging the flow in each, so that, in their judgment, 

 the lower ends of the furrows would be nearly reached 

 on their return in the morning. After watering once 

 begins, it is kept up until the crop is matured, going 

 over the field every 10 to 15 days. 



In the growing of potatoes by irrigation, it is a 

 matter < of the greatest importance that the ground 

 shall be kept well moistened continuously after the 

 tubers have begun to form, so that they shall be kept 



