IRRIGATION. 



By E. E. OLDING. 



Where the effective rainfall is deficient for the production of 

 crops, an abundance of water available for irrigation is one of the 

 most valuable assets a plantation can have. 



Wherever water can be put on the land by gravit.v, this s.ystem is 

 recommended, even if the cost of canals i>i much greater than the cost 

 of pumping water, as the pumps, boilers and pipe lines necessitate ii 

 much greater expense for maintenance. Where canals are well con- 

 structed the cost of u|)-keep is ver.v small. 



In the Arecibo District the rainfall as shown b.y the following 

 table is deficient during an average of five months in each year. The 

 minimum quantity of water necessary to produce a fair growth of 

 cane, (as determined by the Hawaiian Experiment Station in 1903) is 

 taken at 1 inch per week. Taking this as a basis we get the following 

 shortages of water for Arecibo (see also table of rainfall at Arecibo.) 



TABLE No. III. 



SHOWING MINIMUM SHORTAGE OF RAINFALL AT ARECIBO. 



Year 



1900 1901 1902 1903 1904 1908 1909 1910 1911 



January.... 1.50 0.96 3.85 2.47 2.00 2.00 2..36 1.30 2.15 



February... 3.13 2.60 3.85 2.75 — _ 2.31 1.25 2.35 



March 2.45 — — — — o.72 2.79 2.15 



April 0.93 0.73 0.86 125 



May 0.84 0.83 0.80 — 1.13 3.70 



June 0.90 1.18 73 — 0.45 



July 1.23 1.44 1.45 



August.... — 2.72 



September. 0.41 — 0.74 1.20 



October 0.62 0.13 0.75 0.05 



November.. 2.87 2.00 2.80 



December.. 1.35 



Total 8.33 6.28 9,06 7.05 9.59 6.42 9.52 9.83 12 95 



N. of months drouths 5 3 3 4 7 6 5 7 8 

 Average of months of drouth, 5.33 



Inches 



The cost of pumping water as determined at the Ewa Plantation 

 in Hawaii, where 64,750,000 gallons of water are pumped daily to an 

 average height of 91 feet, maximum 205 feet, using oil as fuel, at the 

 cost of $1.40 per barrel, four barrels of oil being equivalent to one 

 ton of coal, (which formerly cost $8.00 per ton) cost &% cts. for 



