258 SOILS 



more in diameter at the end of each furrow, plugged 

 when not in use. A wooden flume is commonly 

 made of soft redwood timber, 16 feet long and 

 8 inches wide, with collars 2x3 inches every 8 

 feet one in the middle and one at the joint. In 

 garden irrigation on a small scale a wooden V- 

 shape flume may be placed at the head of the rows 

 and the water may be drawn through small holes 

 cut into the sides or top of the flume and furnished 

 with plugs. 



Plowing Irrigation Furrows. The furrow may 

 be plowed out with one of the many special irri- 

 gation plows, but a shallow-furrowing plow will 

 answer. The furrows should run in such a way 

 that they follow the contour, so as to enable the 

 water to barely trickle down to the ends of the 

 furrows without washing. If the slope is quite 

 sharp the rows of plants and the irrigation furrows 

 must run diagonally across the slope from the head 

 ditch. Water is turned into several furrows at 

 once; when it has reached the ends of the furrows 

 it is shut off at the head ditch and more furrows are 

 filled. 



The amount of water that the soil receives de- 

 pends very largely upon the grade of the furrows. 

 If it is slight, the water moves sluggishly and more 

 sinks into the soil before it reaches the end of the 

 furrow than if the furrow is sharp. Do not allow 

 enough water to enter the furrows to overflow 

 them. The water is distributed from the furrows 

 sidewise all through the soil by capillary action 

 It creeps from particle to particle until it meets 

 the water spreading sidewise from the adjoining 

 furrow. 



Distance Apart and Length of Furrows. The 

 best distance apart for irrigation furrows depends 



