CROP DEVELOPMENT UNDER IRRIGATION 169 



actually used, though wastefully, in many of the irrigated 

 sections. 



With the smallest quantity of water, nearly 45 per 

 cent of the total wheat crop was seed; as the water was 

 increased, the percentage became smaller and smaller, 

 until, with 50 inches, the percentage of seed in the crop 

 was less than 33 per cent. In a similar manner, the seed 

 in oats fell from 64 to 57 per cent as the water was 

 increased; in barley, from nearly 51 to a little over 38 

 per cent, and in corn, from nearly 52 to about 43 per cent. 



That is, under irrigated field conditions, the law 

 which has been so frequently determined in pot experi- 

 ments has been fully confirmed: namely, as the water 

 available to plants increases, the proportion of seed in 

 the plants decreases. This is naturally of the deepest 

 significance to the irrigation farmer, for not only does 

 the total yield of the crop per unit of water decrease 

 largely as -more water is used, but the proportion of the 

 more valuable parts of the plant decreases also. The 

 meaning of this is that, if the yield per acre-inch of 

 water of the whole wheat crop is diminished as more- 

 water is used, the yield of grain is even more largely 

 decreased. The grain farmer cannot, therefore, by any 

 process of reasoning convince himself that it is desirable 

 to use very large quantities of water for the production 

 of his crops. (Fig. 31.) 



It may be said, in this connection, that the prevail- 

 ing idea that grain grown with little water is not so full 

 and plump as that produced with more water, is erro- 

 neous. This phase of the matter will be discussed in 

 Chapter XI. 



109. Other plant parts. The development of crops 

 under the influence of irrigation as here outlined is fairly 



