380 



THE IREIGATION AGE. 



water combined with the rainfall has averaged 33 y 2 

 inches. This means that these orange and lemon trees 

 have been kept growing continuously the year round on 

 an amount of water less than the rainfall of Iowa. 



Regarding the evaporation losses, it was shown that 

 a heavily irrigated orchard soil lost by evaporation at 

 the rate of over four inches per week, that a soil that 

 was fairly moist on the surface and in good condition 

 for crop growth lost about one inch per week, while a 

 dry soil lost only one-fourth of an inch per week. The 

 usual custom in this part of California is to water only 

 once in every four or six weeks; to water the water in 

 deep furrows; and to cultivate thoroughly after each 

 watering to a depth of from six to ten inches. In this 

 way, much of the water which would otherwise be lost 

 by evaporation is saved. This, however, is not the prac- 

 tice in many parts of California, and more particularly 

 in many of the mountain States. Cultivated crops are 

 frequently irrigated and then left uncultivated until 



cent, or 75 per cent in all. This would leave only 25 

 per cent to nourish the orange trees. 



The great waste of water caused by uneven and 

 rough surfaces and careless application are too common 

 to call for any extended remarks. Then, too, some irri- 

 gators are so generous that they have always water to 

 spare. They give the county roads a good soaking 

 every time they irrigate the bordering fields. One can't 

 find fault with the irrigator for working only ten 

 hours a day, but unfortunately while he is sleeping or 

 resting, 'the water is usually running to waste. Lack 

 of constant attention may therefore be reckoned as an- 

 other cause of much waste. 



Next to the loss by evaporation, and frequently 

 exceeding it, is the loss in transmission. In such 

 channels as are used at the present time in the West 

 for the conveyance of water one has usually to dis- 

 count the flow at the head 33 per cent. As a rule, 

 the cultivated fields do not receive more than 66 gallons 



How Sugar Beets grow in Southeastern Idaho along the American Falls Canal and Power Co.'s Canal. 



the next irrigation water is applied. Summing up this 

 question of evaporation losses in irrigation, it is safe 

 to assert that about one-half of the water which is ap- 

 plied to fields escapes into the atmosphere from the 

 surface of the soil without in any way benefiting the 

 plant. It is rather a positive injury in that during 

 the process, it forms a crust on the surface which pre- 

 vents air from getting to the roots and tends to draw 

 up moisture from beneath. Some of the means that 

 may be employed to lessen this great waste will bo 

 referred to later. 



In irrigating orchards under the Gage Canal an- 

 other source of waste was the percolation of water into 

 the porous subsoil, and its subsequent passage to lower 

 levels. In one orchard tract of ten acres the part of 

 one irrigation lost by deep percolation was 28 per cent, 

 and by evaporation from the surface of the soil 47 per 



out of every 100 gallons which pass through the upper 

 headgates. 



In all these losses caused by evaporation, deep 

 percolation, careless application, and leaky ditches, it 

 is not surprising that only a small part of the water 

 diverted from the natural streams finds its way to the 

 fibrous rootlets of plants and is drawn up by them 

 through the stem by the foliage. 



WATS AND MEANS OF INCREASING THE DUTY. 



The irrigation department of the University of 

 California, working in conjunction with the Office of 

 Experiment Stations, is now carrying on experiments 

 on the cheapest, and at the same time, the most effi- 

 cient linings for canals. The tests are made in twelve 

 separate ditches. Various kinds of cement concrete, 

 cement plaster, crude oil, asphaltum. puddled clay 

 and earth are iised. In the course of a few months the 

 results will be ready to be published. 



