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 
