Arizona AcKKiLirRAL Expkkimknt Station- 453 



the appearance of the fractured surfaces, the more porous tile ap- 

 pearing damp or wet and showing more or less alkali salt in the 

 fracture, while the denser tile were dry and absolutely free from 

 any signs of alkali. The densest and strongest tile were those that 

 had been mixed with quaking or wet consistency, and the tests have 

 established definitely that drain tile for strongly alkaline soil should 

 be mixed wet. One series of tile had been dijiped or painted with 

 cement grout ; the grout was intact in its original condition. Tar 

 coating was less eftective than the gruut, and ferrous sulfate in 

 the mixing water was shown to be of no value. Both hand-tamped 

 and machine-made pipe were among those tested, and both classes 

 showed definitely that dense concrete is not affected by alkali. 

 This conclusion is substantiated by information received concerning 

 tests on similar series of drain tile buried in alkali soil in other 

 Western states and tested by the U. S. Bureau of Standards. 



It can be stated, then, that hand-made drain tile of wet con- 

 sistency*, or high grade machine-made pipe is entirely safe for 

 drainage projects in Arizona. The reason why such pipe should 

 be used in preference to clay tile is because of the great saving in 

 cost. 



USE AND WASTE OF IRRIGATION WATER 

 Bulletin 88, under the above caption, was published in May, 

 1919. It is the result of observation and study relative to methods 

 of irrigation during the past fifteen years. It discusses the useful 

 function of irrigation (transpiration), and classifies the various 

 losses to which irrigation supplies are subject, offering many sug- 

 gestions for reducing the losses to a minimum. 



The efficiency of irrigation is defined as the ratio of that portion 

 of the water actually utilized by the crop to the total quantity ap- 

 plied to the land. It is the farmer's province to make this ratio 

 as high as possible. 



The bulletin was written particularly for those districts in Ari- 

 zona like the Salt River Valley where the water table has risen to 

 dangerously high levels, and for the pump irrigators, whose water 

 supplies are so costly that the water must be conserved to the 

 utmost limit. 



THE CONTINENTAL RUBBER PLANTATION 

 The report, on the basis of which the rubber plantation was 

 located at Continental, near Tucson, was made by the Irrigation 



*See Bulletin 86, Arizona Experiment Station, page 91. Much cement pipe of 

 this class is being made in the Salt River Valley at the present time. 



