CHAPTER VIII 

 CROP DEVELOPMENT UNDER IRRIGATION 



THE total yield of a crop is, usually, of first impor- 

 tance; but, frequently, a particular part of the plant 

 commands a much higher value than some other part. 

 Thus, the seed of wheat, oats, barley, rye, corn and the 

 other grains, has a much higher value than the straw; 

 and the tops of sugar beets have comparatively little 

 value, while the roots bring high money returns. For such 

 plants, it is as important to regulate the proportion of 

 plant parts as to produce a large yield of the whole plant. 

 The whole crop of alfalfa and the hay crops generally, is 

 sold, but the nutritive value of the hay, per pound, 

 depends on the relative proportion of the stalks and 

 leaves, since the leaves are much more nutritious than are 

 the stalks. The farmer prefers leafy plants, and it is 

 important to know under what conditions of irrigation 

 the largest proportion of leaves may be obtained. 



In yet another way is this matter important. The 

 grains, the grasses and many other crops are harvested 

 only for the parts above ground. The roots are left in 

 the ground to decay and have no direct money value. 

 The substances elaborated in the plant are rather easily 

 moved from place to place, and, under certain cultural 

 treatments, it is conceivable that much of the nutritive 

 material of the plant may move into the roots and remain 

 there when the plant is harvested. The farmer needs to 

 know, therefore, under what conditions of irrigation the 



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