106 THE POTATO 



a sufficient head of water is taken from the lateral 

 to supply about twenty corrugations. This is run 

 into the sub-laterals, and from these distributed 

 to the corrugations. This breaks up the head of 

 water into small streams that can be more easily 

 handled. A controlling device to regulate these 

 small heads of water may be made from 1x4 inch 

 stuff nailed together, making a box four inches 

 square outside measurements and about three feet 

 long. This box is placed between the lateral and 

 sub-lateral low enough to intercept the flow of 

 water. The sub-lateral is generally a plow furrow 

 with the dirt thrown down hill. Dirt dams are 

 placed in it at proper intervals (about every 

 twenty corrugations) to force the water out to the 

 corrugations. 



"It is sometimes necessary to place checks im- 

 mediately below the diversion points in the lat- 

 eral in order to raise the water level high enough to 

 force the water into the corrugations. These 

 checks are boxes or gates put in ditches or lat- 

 erals through which the water is made to pass. 

 The height of water maintained above the check 

 is regulated by building up the opening (with 

 narrow strips beginning at the bottom) through 

 which the water passes. Canvas dams can also 

 be used as checks when they are properly made. 

 Sacks filled with dirt can also be used for diver- 

 sions. 



"The corrugation or furrow system is the 

 method best adapted for the watering of all root 

 crops. Potatoes show the bad effects of even a 

 break between the furrows and consequent flood- 

 ing. For potatoes the furrows are made quite 

 large, the rows being ridged and furrows made be- 

 tween the rows. Sometimes the best method for 



