CHAPTER VII 



THE IRRIGATION OF THE CANE 



ALTHOUGH the greater part of the sugar cane crop of the world is produced 

 under natural conditions, no inconsiderable proportion is grown under 

 irrigation. The districts where irrigation forms an obligatory feature of 

 cane cultivation are the islands of Oahu, Maui, and Kauai, in the Hawaiian 

 Archipelago, Peru, Egypt, British India, the small area in the south of 

 Spain, and a few plantations in the Black River district of Mauritius. The 

 combined production of these areas now (1919) amounts to about 3,500,000 

 tons of sugar or about 25 per cent, of the world's production. Partial 

 irrigation is also practised in Java to a considerable extent, but the conditions 

 here are such that crops can be and are grown under natural conditions, 

 and irrigation is a minor rather than a major part of the economy of a planta- 

 tion. Limited areas are also irrigated in Cuba in the Guines district, in 

 Guantanamo, at Nipe Bay and at Constancia (Cienfuegos), and some irrigated 

 cane is produced also in Jamaica, Porto Rico, Formosa and Portuguese 

 East Africa. 



Water used in irrigation is measured in a number of systems : As a 

 flow per unit of time, or as a depth per unit of area. The British flow unit 

 is the cubic foot-second, or ' cusec ' usually referred to the acre. The metric 

 system uses the litre-second referred to the hectare (i c. ft. = 28-2 litres 

 and i hectare =2-47 acres). The British depth measurement is the acre 

 inch equal to 101-5 l n g tons, 3,652 c. ft., 22,736 imperial gallons, 27,294 

 U.S. gallons and 103,130 litres. Hawaiian practice reckons in so many 

 million gallons per day. 



Methods of Irrigation. Hilgard 1 distinguishes the following methods : 

 i. Surface sprinkling. 2. Flooding (a) By lateral overflow from furrows 

 and ditches; (b) by the check system. 3. Furrow irrigation. 4. Lateral 

 seepage from ditches. 5. Basin irrigation. 6. Irrigation from underground 

 pipes. 



Of these methods, the first, second, third and fourth find application 

 in one or other of the cane-producing areas. These methods are described 

 under the regional headings. 



Hawaiian Islands. 2 The privately owned irrigation works in this locality 

 are unparalleled in other districts, and at December 31st, 1914, represented 

 a depreciated investment of $12,818,512, though the actual capital expendi- 

 ture has been very much greater. From actual capital expenditures that 

 have been published may be quoted : 



Ewa. Total cost of pumps delivering 22,000,000 gallons daily, 375,000. 



Koolau ditch in Maui, 10 miles long and delivering 80,000,000 gallons 

 daily, 91,000. 



Olokele ditch in Kauai, 13 miles long and delivering 60,000,000 gallons 

 daily, 75,000. 



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