WATER INFLUENCES COMPOSITION 269 



Even a casual study of this table shows that the 

 quantity of water used influenced the composition of 

 the plant parts. The ash and the fiber do not appear 

 to be greatly influenced, but the other constituents 

 vary with considerable regularity with the variations 

 in the amount of irrigation water. The protein shows 

 the greatest variation. As the irrigation water is 

 increased, the percentage of protein decreases. In 

 the case of wheat the variation was over 9 per cent. 

 The percentage of fat and nitrogen-free extract, on the 

 other hand, becomes larger as the water increases. 

 That is, crops grown with little water, as in dry-farm- 

 ing, are rich in the important flesh- and blood-forming 

 substance protein, and comparatively poor in fat, 

 sugar, starch, and other of the more abundant heat- 

 and fat-producing substances. This difference is of 

 tremendous importance in placing dry-farm products 

 on the food markets of the world. Not only seeds, 

 tubers, and roots show this variation, but the stems 

 and leaves of plants grown with little water are found 

 to contain a higher percentage of protein than those 

 grown in more humid climates. 



The direct effect of water upon the composition of 

 plants has been observed by many students. For 

 instance, Mayer, working in Holland, found that, in a 

 soil containing throughout the season 10 per cent of 

 water, oats was produced containing 10.6 per cent 

 of protein; in soil containing 30 per cent of water, 

 the protein percentage was only 5.6 per cent, and in 



