THE IRRIGATION AGE 295 



In making up these figures, however, Mr. Cowan qualified them by saying that 

 hey are for the full capacity of the ditch, which is not always full when required, 

 and is only partially compensated for full flow by the rainfall. * The ave- 



rage yield of the plantation is given at 5.6 tons of sugar per acre for plant cane and 

 4 tons for ratoon crop. * * He summarizes by stating that to raise 1 pound 



of sugar requires about 51.8 cubic feet of water. 



There are so many elements of uncertainty included within the 

 foregoing statement that it must be coasidered as merely an approxi- 

 mation to the truth. The report further states: 



On the Kekaha plantation, Kauai, water is obtained by pumping to a height of 

 18 to 36 feet, en average of about 27 feet. The delivery of the water is contracted 

 for at the rate of $35 per acre per unnum. The contractor is required to deliver 

 sufficient water to irrigate 700 acres every ten days to an average depth of 4 inches 

 at each watering. The duty thus performed, presuming the quantity contracted for 

 is fully delivered, would be 59? acres per cubic foot per second. The pumping is 

 done during ten hours each day. The three pumps required to have a capacity of 

 7,000,000 gallons per day each. Coal costs $11 per ton at the pumps. A very un- 

 usual yield is reported from this plantation. Ratoon crops for seven consecutive 

 years are said to have produced an average of 5 tons of sugar per acre each year. 



In summing up their observations, Messrs. Schuyler and Allardt 

 say that a greater duty than 60 acres per cubic foot per second can 

 not possibly be considered safe; or in other words, at least 5,000,000 

 gallons per acre are required to make the crop. 



The data and conclusions furnished by Schuyler and Allardt have 

 been given at length, for the reason that they formed the basis of 

 computations some ten years ago and are still followed by the older 

 plantation authorities. During the past six months two persons who 

 are connected with the opening up of new plantations assured the wri- 

 ter that those estimates ''were not conservative enough to be safe, 

 and that in their calculations and provisions they were providing for 

 not less than 6,000,000 gallons^of water per acre for the crop. The 

 more conservative estimates of those gentlemen are not based upon 

 any ascertained knowledge of the requirements of the soil and crop. 

 They are merely the result of a wish to be safe. As a consequence, 

 when the basis of 6,000,000 gallons per acre for the crop becomes the 

 practice, some other gentlemen of conservative mind who also wish to 

 be safe will appear who will think 7,000,000 gallons a necessary provi- 

 sion. At present the practice upon the plantations is not resting 

 upon ascertained requirements which can be arrived at only by the 

 aid of a knowledge of the physical laws that have been set forth and 

 by actual tests involving the determination of the amount of water 

 that the crop during the different stages of growth requires in given 

 conditions of soil and climate. 



STUDY OF IRRIGATION AT THE HAWAIIAN EXPERIMENT STATION, 



In view of the absence of established data bearing upon the actual 

 requirement of the sugar cane in the conditions of soil and climate of 

 the Hawaiian Islands, and also on account of the great variations that 



