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IRRIGATION. 



In the Sahara, irrigation is practised by means of trenches, 

 where no crops are grown under the palms. These are excavated 

 alongside of tlie trees and occasionally filled with water. Where 

 barley or alfalfa is grown, the land is divided up into small beds 

 from 10 to 30 feet in diameter, which are surrounded by a raised 

 rim. The bed can then be flooded. On account of the alkalinity 

 of the soil, it is found especially necessary to provide a good 

 drainage system. 



Mr. Fairchild gives the following account of the method of irri- 

 gation practised at Dassorah : — 



' The method of planting is determined by the irrigation ditches, 

 which are large (often 3 feet by 3 feet) and cut the ground up 

 into small rectangular peninsulas, 10 to 15 feet by 20 to 30 feet 

 in size. On each peninsula two, or sometimes three, palms are 

 set. Often the peninsulas are much larger and hold from four to 

 five or even as high as ten palms. The size of these peninsulas 

 depends somewhat on the permeability of the soil and the height 

 to which the irrigation water rises in the ditches. On an average 

 100 palms are planted to a "djerib," which unit of measure is a 

 trifle less than an acre. ' 



'In order to prevent the waters receding too quickly from the 

 canals when the tide falls, dams of mud are built, and pipes, or 

 the hollow trunks of palms, are run through them, which permit 

 the water forced into the canals by the rising tide to flow away 

 slowly. The length of time during which the canals are filled 

 with water is more or less under the control of the proprietor, and 

 as the supply is practically unlimited, no tax of any kind is paid, 

 nor is any regulation necessary regarding its use. 



' In short, the Bassorah date grower has only to see that his 

 ditches are kept in order, which is an easy matter where the soil 

 is as pure adobe as the clay of a brick-yard, and the back water 

 of the river will fill and empty them twice every 24 hours. The 

 conditions of this form of irrigation, which might be called a tidal 

 one, are quite ideal and so far as known are found on such a scale 

 no where else in the world. ' 



POLLINATION OF THE DATE PALM. 



Male and female plants are produced in about equal numbers. 

 As has been stated, date palms are pollinated in the wild state by 

 wind, but where the trees are pollinated artificially, only one 

 male tree is required for every 1 00 females. 



'The male flower cluster of the date consists of a stalk bearing 

 a considerable number of short twigs to which the flowers are 

 attached, the whole contained in a sheath, at first entirely closed, 

 but which finally ruptures, disclosing the flowers. The Arabs cut 

 the male flower clusters from the trees shortly before the flowers 

 have fully opened. The separate twigs to which are attached the 

 male flowers are from 4 to 6 inches long, and bear probably from 

 twenty to fifty male flowers, each containing six anthers full of 

 pollen. One of such twigs suffices to pollinate a whole female 



