THE IRRIGATION OF THE CANE. 



Eegnoso estimates that in Cuba the majority of the plantations require every 

 ten days an irrigation equal to 1000 cubic metres per hectare, or 40 tons per 

 acre per day. 



Egypt. In Egypt, according to Ronna 3 , the cane is watered as soon as 

 it is placed in the furrow in the month of February ; other irrigations follow 

 every ten days until the end of August. From this time up to the end of 

 October every fifteen or twenty days, after which irrigation is stopped. The 

 water required at each irrigation is, according to Tiemann 4 , 1000 cubic metres 

 per hectare. 



Demerara. The method by which fields are irrigated will be easily 

 understood on referring to Figs. 38 and 39 ; a drain indicated by the line g is 

 dug parallel to the cross canal c, and connected to it. Down the centre of the 

 beds irrigation drains 15 inches wide and 9 inches deep are dug, along which 

 the water runs into the main drain /and thence to the drainage trench c. 



In the * English ' fields, the main drainage trench is dammed at the 

 proper points and the navigation water is cut into the field so that the field 

 or fields can be swamped. 



Although the water available in the rivers is beyond realization, irrigation 

 is but little practised and its results are often harmful ; the best ever 

 accomplished is the prevention of the entire loss of the crop. To the student 

 of sugar literature, soil and topographical conditions have a great resemblance 

 to those of Java where irrigation succeeds; the only occasions when the 

 writer has seen irrigation tried was in "English" fields when a system of 

 lateral seepage obtains. Harrison 5 has demonstrated the alkaline nature of the 

 subsoil waters of this district and their toxic action ; such a system would 

 bring these waters to the surface, and here may lie the cause of the failure. 

 With a system of subsoil drainage the possibilities of irrigation are very great. 



Java. The irrigation works in Java are of great magnitude, and are 

 entirely under state control. Conditions here are entirely different from those 

 in Hawaii, due to the enormous native population (over 30,000,000) whose 

 interests in the water available (used by them mainly in the rice crop) are 

 zealously guarded by the Dutch Government, which apportions the amount of 

 water to be used by the European cane planters and by the native peasants. 



Geerligs 6 has given the following details of cane irrigation in Java : 

 " In consequence of the intensive cultivation of the cane in Java the soil 

 is quite dried to a considerable depth and absorbs an enormous quantity of 

 water. This can be estimated at two or three hectolitres per bouw* per second 

 (equal to 3 to 5| cusecs per acre) at planting ; if at the age of two or three 

 months the soil is gradually saturated, in the absence of rain, only sufficient 



*A bouw does not seem to be a very definite area ; in one authority I find it put equal to a 

 hectare or 10,000 square metres ; in another to 500 Rhynland roods or to T67 acre. In a paper by 

 Kanmerling dealing with the water transpired by the cane a bouw is taken as 8000 square 

 metres, i.e. 1-97 acre. According to Geerligs, 1 bouw equals 500 square Rhynland roods or T75 

 acres. I have translated the quantities in this section into cusecs per acre, taking the bouw as 

 two acres, and the hectolitre as 3'525 cubic feet. (N. D.) 



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