44 



METHODS OF IRBIGATION. 



Of soinethiii<r over 60 plants described in the preceding pages 25 

 use the fiirrcnv system, usnahy siipi:)Iying wat(>r through pipes and 

 hose, 17 use hose sprinkling, 8 use single water witches, and 18 use 

 midtiple water-witeh systems. Twelve of these plants use more 

 than one system, and about 10 are not reported. While the data 

 are too variable to form a basis for reliable statements as to relative 

 advantages, it is interesting to notice what averages the data show. 



The size of a single stream of water averages 24 gallons per minute 

 for each furrow, 44 for each hose nozzle, and about 4 gallons per min- 

 ute for each sprinkler used. The time during which water is run in 

 one place averages half an hour for the furrow system and nearly an 

 hoiu' with sprinklers. None of the plants using fiuTows or single 

 sprinklers requires more than one man to look after the water, usually 

 using not more than half of his time during an irrigation. Where 

 hose sprinkling is used the entire time of one man is required for each 

 nozzle during an irrigation, the average number of men being three. 

 With multiple sprinklers, owing to the necessity of moving long lines 

 of pipe, a number of men are required for a short time when the water 

 is changed, only a small fraction of their time being taken for this pur- 

 pose. The number of men required averages three, the work of irri- 

 gation taking about one-fourth of their time. Where a complete sys- 

 tem of piping is installed, one man can look after an entire plant. 



In estimating the labor cost of one irrigation, the actual time put in 

 by each man must be considered. In the following averages lal)or is 

 taken at $1 .50 per day, and it is assumed that five minutes are required 

 to change the water in a furrow or to move a sprinkler. AMiere mul- 

 tiple witches are used, five minutes are allowed for moving the first of 

 a system of bars, and three minutes for each additional bar, except on 

 the larger places where a number of men must be called from greater 

 distances, in wliich cases ten minutes are allowed for the first bar. On 

 this basis the labor cost of one irrigation by furrows runs from SO. 30 to 

 $1.20, averaging $0.75 per acre. With hose sprinkling the average is 

 $1.80 per acre; with single witches, $1.12, and with nudtiple sprinklers 

 $2.40, ranging in the latter case from $0.45 to $8.70 per acre. The 

 depth applied, however, is 1.3 inches by furrows, 0.6 inch by hose 

 sprinkling, 0.3 inch by single sprinklers, and 1.8 by multiple witches; 

 making the average labor cost of applying 1 acre-foot of water, $7.10 

 by furrows, $34.80 by hose, $34.40 by single sprinklers, and $16.10 by 

 multiple sprinklers, but where a complete system of pipes is installed 

 the cost runs as low as $3.50 per acre-foot. It should also be noticed 

 that the labor of applying water with sprinklers is not increased by 

 lengthening the time and the amount of water used since only a defi- 

 nite number of changes are required to irrigate a given piece of 

 land once. With hose or furrow irrigation the labor is proportional to 



