IRRIGATION OF CEREALS 247 



the delay occasioned by the necessary interval between 

 irrigation and plowing. For that reason, the soil is fre- 

 quently plowed early in the spring, irrespective of dry- 

 ness, the seed planted in the dry soil, and then irrigated. 

 The water thus added immediately favors germination 

 and furnishes also a supply of water for the young plant. 

 Both of these methods of early irrigation are giving satis- 

 factory results. 



After germination and first growth, irrigation should be 

 delayed as long as possible. When water is needed, the 

 grains, which normally are of a light green color, become 

 darker green, and in protracted dryness the lower leaves 

 become definitely yellow. If the soil becomes too dry, 

 the crop may be permanently injured; in fact, the soil 

 below the surface should remain fairly moist throughout 

 the growing season. If the seed has been planted in well- 

 saturated soil, since young plants require little moisture, 

 several weeks will elapse before irrigation will be necessary. 



During the early stages of growth, the plant devotes 

 its energies to the preparatory work of gathering carbon 

 from the air and mineral matters from the soils, and of 

 combining these into organic forms. The period of most 

 rapid growth comes shortly before or at the time of flower- 

 ing. At the time of "boot," that is, when the heads just 

 begin to show, it is well to apply water, and again, if 

 needs be, at the time of seed-formation. It is most impor- 

 tant, however, that the soil be not dry at the time of 

 flowering; for, if there is an abundance of water at that 

 time, a ready transfer of nutritive materials from stalks 

 and leaves to the heads is made possible. Moreover, 

 water applied when the seeds are "filling out" will result 

 in increased grains at the expense of the straw. 



It may be that the answer to the question concerning 



