RELATION OF WATER TO DRY MATTER 17 



tion of each pound of dry matter is very much larger 

 under arid conditions, as in Utah, than under humid 

 conditions, as in Germany or Wisconsin. It must be 

 observed, however, that in all of these experiments 

 the plants were supplied with water in a somewhat 

 wasteful manner; that is, they were given an abun- 

 dance of water, and used the largest quantity pos- 

 sible under the prevaihng conditions. No attempt 

 of any kind was made to economize water. The 

 results, therefore, represent maximum results and 

 can be safely used as such. Moreover, the methods 

 of dry-farming, involving the storage of water in 

 deep soils and systematic cultivation, were not em- 

 ployed. The experiments, both in Europe and 

 America, rather represent irrigated conditions. There 

 are good reasons for believing that in Germany, 

 Wisconsin, and Utah the amounts above given can 

 be materially reduced by the employment of proper 

 cultural methods. 



In view of these findings concerning the water 

 requirements of crops, it cannot be far from the truth 

 to say that, under average cultural conditions, ap- 

 proximately 750 pounds of water are required in an 

 arid district for the production of one pound of dry 

 matter (Fig. 7). Where the aridity is intense, this 

 figure may be somewhat low, and in localities of sub- 

 humid conditions, it will undoubtedly be too high. 

 As a maximum average, however, for districts inter- 

 ested in dry-farming, it can be used with safety. 



