IRRIGATION OF FIELD CROPS. 21 5 



much so that the miller finds it necessary to thoroughly 

 wet the grain before grinding. This wetting process 

 makes the bran tough, so that it is removed by means 

 of the rollers almost entire. 



Wheat by Subirrigation. — The preparation of 

 the soil for a crop of subirrigated wheat should begin 

 ten months before sowing the seed. If peas were 

 raised as a hay crop on ordinary far- western mineral- 

 ized land the year previous, the grower would secure 

 the double benefit of a large amount of cheap forage 

 and an increased yield of wheat. In the subirrigated 

 districft of the San I^uis valley, in Southern Colorado, 

 where this system prevails more extensively, perhaps, 

 than any other place in the world, the land is flooded 

 in the early spring while water is abundant and carries 

 sediment for enriching and settling the soil and germi- 

 nating weed seeds. When the weeds are three to six 

 inches high, plowing is begun with four horses abreast 

 and a double plow, turning the soil from four to seven 

 inches deep. No harrowing is necessary and very lit- 

 tle is done except where weeds spring up on the sum- 

 mer fallow, which is seldom the case. The land is left 

 without further care until the following fall or spring, 

 when vitrioled wheat is drilled in at the rate of sixty 

 pounds an acre. The drill is set to run three inches 

 deep, or as deep as is necessary to put the seed in moist 

 soil. As soon as convenient after drilling the field is 

 ditched for the subbing. 



If not previously done, a head ditch is made along 

 the highest side of the field to receive the water from 

 the supply lateral and distribute it to the irrigation 

 trenches. These latter are made in parallel lines from 



