88 EXPEEIMENT STATION EECORD. 



$20 to $40 per acre. (4) The largest item of cost is the fixed charges. In 

 order to reduce these charges the plant should be used as much as possible. 

 One pumping plant should, if possible, serve two or more ranches." 



Comparative tests of a new centrifugal pump and an old stock type showed 

 the efficiency of the former to be one-third, higher than that of the latter. The 

 new pump was a horizontal single stage pump having two outboard ring oiling 

 bearings, water sealed gland, vacuum-proof grease cup, nonoverloading enclosed 

 impellor, and automatic water balance. 



The drainage of irrigated land, R. A. Haet {TJ. S. Dept. Agr. Bui. 190 

 {1915), pp. 34, figs. 22). — It is the puriiose of this bulletin to present in concise 

 form the fundamental principles upon which the reclamation of water-logged 

 and alkali lands is based, to describe typical conditions and the best methods 

 of treating them, and to give practical advice as to actual operations. 

 " Drainage practice in the arid section differs greatly from that in the humid 

 region. . . . Drainage experience in the humid section avails little in dealing 

 with the problems of draining irrigated lands. For this reason literature on 

 the general subject of drainage should be used with caution, as the difference 

 in conditions between the arid and humid regions has been clearly recognized 

 only within the Inst few years." 



The specific objects of draining water-logged and alkali lands are "(1) to 

 lower the ground-water table to such a depth that the moisture and air condi- 

 tions within the root zone are properly balanced, (2) to provide an outlet for 

 percolating water, so that fluctuations of the ground-water table within the 

 root zone will be prevented, (3) to effect rapid removal of the excess moisture 

 resulting from spring thaws, and (4) to provide an outlet for the downward 

 moving water used to dissolve out the injurious salts. . . . 



" The most important factors affecting the design of a system of drainage for 

 irrigated land are the source and movement of the damaging water. , . . Per- 

 colating irrigation water usually is the cause of the injury, and this may have 

 its movement downward through the soil of the tract being irrigated, laterally 

 through pervious strata extending back under higher lands, or upward from 

 pervious strata having considerable depth and connecting with distant sources 

 at a higher elevation." 



In determining the quantity of water that will be developed and for which it is 

 necessary to provide an outlet, it is stated that " for tracts np to a few hundred 

 acres in area and having average soil and subsoil, the simplest method, and 

 one which has proved reliable, is to determine the irrigation supply and to 

 provide a drainage capacity of one-third that amount of w\ater. As the size 

 of the tract increases, however, this coefficient should be decreased. If the 

 subsoil be clay, provision for one-fifth the irrigation supply will suffice for small 

 tracts. In areas of a square mile or more, it is usually sufficient to provide for 

 a run-oft" of from 1^ to 2i cu. ft. per second for each square mile, depending 

 upon the porosity of the soil and the duty of the irrigation water. ... In lands 

 [underlain by gravel] it is the area that is contributing the damaging water, 

 not the area to be drained, that must be taken into consideration." 



It is stated that in determining the required capacity of a drainage system 

 in addition to the surface survey subsurface examinations should be made to 

 gain information as to the nature of the soil, its stratification, water-carrying 

 capacity, and capillarity. "In the design of an open canal the important 

 points to be considered are the effectiveness of the drain, its carrying capacity, 

 its mechanical construction, and its maintenance in good condition. . . . [The 

 depth 1 should never be less than G ft., presuming that the maximum depth of 

 flow will be 1 ft., and 8 ft. would be a better minimum. ... A berm of not 



