GROWING BY IRRIGATION. 283 
since if they run in a direction across the slope there 
will be danger of their filling and the water fail 
of reaching the points aimed at. The furrow method 
will do more with a small amount of water than any 
other except subirrigation by means of tiles. 
The Flooding System.—The most common way of 
irrigating alfalfa in our West is by flooding. To 
prepare land for this system one puts in ditches on 
contour lines, the upper one to bring water to the 
field, below another to catch the waste water and 
collect it for the part of the field below. 
The distance apart of these head ditches, as they 
are called, is determined by the nature of the soil, 
slope and the amount of water to be had. Usually if 
they are from 400’ to 1,000’ apart it will be well, 
with an average distance perhaps of abeut 500’. 
Much here depends on the nature of the soil. There 
are soils where it is well to have these ditches as 
near as 200’ feet or even closer together. Much 
of course depends upon the head available. If there 
is not much head the leading ditches should be closer 
than if there is a flood of water. The ditches while 
following contour lines rather closely ought to have 
enough fall so that the water will flow freely in them. 
Preparing the Land for Flooding—The contour 
ditch is made first, strong, with a good bank. Be- 
low it a lesser ditch, close up; this to distribute the 
water. The field should be leveled as well as pos- 
sible. Upon this leveling will depend a lot of the 
later success or failure of the alfalfa. Work in mak- 
ing the land level is work well spent. It should next 
