ECONOMY IN IRRIGATION. 



685 



the extent of losses by methods still in vogue, the author concludes: 

 " A comparison of the duties secured . . . leads to the belief that it will 

 be possible through improved methods to double the average duty now 

 obtained, so that the quantity now required for one acre will serve to 

 irrigate two. If this can be accomplished it will relieve the scarcity 

 under many canals, put an end to many controversies growing out of 

 such scarcity, lessen the expense per acre for water and immensely 

 increase the productive and taxable resources of the arid states/'* 



In various parts of the old world, where much valuable land has 

 been reclaimed by irrigation, water is distributed in such a way as to 

 secure the best practicable results. At Biskra, Algeria, for example, 

 where the famous Deglet INToor date is grown and the supply of water 

 is limited, an excavation is made around the base of each tree, and this 

 is filled with water, thus greatly lessening the loss that would other- 

 wise result from evaporation, f At Bassorah, on the river separating 

 Persia from Arabia, the extensive date plantations are watered by 

 means of a system of canals which are flooded with each high tide, dams 

 of mud being built with the hollow trunks of palms run through them, 

 which permit the water forced into the canals by the rising tide to flow 

 away slowly. Thus, by taking advantage of favorable natural condi- 

 tions, an ideal system of combined irrigation and drainage is effected 

 at a minimum' of expense. + 



In close agreement with the estimates of Dr. Mead, observations of 

 the writer have shown that plants 

 supplied with water below the sur- 

 face of the ground have made a 

 vigorous growth on a little more 

 than one half the quantity of water 

 that would be required if applied 

 at the surface. To report a single 

 rather striking case — the plants 

 shown in the accompanying figure 

 are photographs of seedlings of 

 palo verde (Parkinsonia, two 

 species) which, with some other 

 desert plants, were under investi- 

 gation. They are here shown as 



they appeared August 10, after being supplied with measured quantities 

 of water since June 12. During this period numbers 1 and 2 each 

 received 71 ounces of water, while numbers 3 and 4 each received but 

 39 ounces, or 55 per cent, as much as 1 and 2. Numbers 1 and 3 



* U. S. Dept. Agr. Office of Expt. Stations, Bui. 86. 1900. 



f Swingle, W. T., ' The Date Palm and its Utilization in the Southwestern 

 States,' U. S. Dept. Agr. Bureau of Plant Industry, Bui. 53. 1904. 



+ Fairchild, D. G., ' Persian Gulf Dates and their Introduction into the 

 United States,' U. S. Dept. Agr. Bureau of Plant Industry, Bui. 54. 1903. 



Seedlings of Pai.o Verde Number 3 

 had as much watt-r as number 4, but it was 

 not economically applied. 



