Arizona Ac.kicultural Exi'Krimknt Station 



409 



TABLK III. — fii;ld tolerance of cotton for alkali, 1919. 



C. N. CATLIN 



THE TEMPE DRAINAGE DITCH 

 In 1916 when water began flowing in the Tempe Drainage 

 Ditch, then still under construction, this department began the 

 study of the changes that take place in the character of the drainage 

 water. Monthly samples, with a few omissions, have been analyzed, 

 giving an almost continuous record for more than three years. The 

 analyses have been published in the Annual Reports of the Station. 

 While the composition has varied considerably from month to 

 month, the general tendency has been for the drainage water to be- 

 come less saline. The first few months, while construction was 

 under way, were marked by excessively salty waters, freshening 

 rapidly as the ditch was extended. The average monthly compo- 



