TWO METHODS OF FARM IRRIGATION'. 247 



am not aware that it has a South African name, I will use the 

 American term for it : furrow irrig-ation. This system is briefly 

 this : — The land to be irrigated is covered with numbers of little 

 furrows a few inches deep and about 3 feet apart. Down these 

 furrows a little trickle of water is allowed to run for several hours 

 at a time, and if the work is well done, the result is like the effect 

 of a long- slow rain. This system has been tried for years in the 

 United States, and has been brought to a high pitch of perfection. 

 It is like a constant, gentle rain, and under certain conditions 

 makes the finest method ever employed for irrigation. The same 

 American whose opinion on flood irrigation I quoted above says of 

 this system : — 



" Suppose you have a square ten acres in an orchard. It will 

 be 220 yards on each side, and you want to put into the soil an 

 equivalent of three inches of rainfall. As a cusec (or a flow of 

 water equal to i cubic foot or 6} gallons per second) equals an 

 inch of rainfall an hour per acre, it will need thirty hours to put 

 the equivalent of three inches of rainfall on the whole. This 

 would be far too slow for flooding, even in 25-foot basins. But 

 if >ou can get i cusec for thirty hours you can do better work 

 with small furrows ; and if you can get it for sixty hours, you 

 can do still better on many soils with only half a cusec, i.e., a 

 flow of 3^ gallons per second. 



" It may seem quite absurd to divide such a stream into two 

 hundred and twenty little ribbons of water, running only a little 

 over a gfallon a minute and spread a yard apart, and expect them 

 to get anywhere. Vet that is exactly what is done in many a fine 

 orchard, and to do it all you need is patience, and to remember 

 that it is the greatest step in advance that was ever made in 

 horticulture, and one that has been so thoroughly tested for thirty 

 ycflrs that it will never go backward. 



" You naturally remark that your soil will never hold up such 

 a little stream to run 220 yards across the 10 acres. That is 

 exactly where you may deceive yourself. It probablv will if you 

 give it time enough. vSuppose you try it. Make a small furrow- 

 about 3 inches deep with the corner of a hoe, turn in such a 

 stream and sit down and watch it. Or, better yet, g-o down 

 town, or go to bed. If it will cross the 10 acres in ten hours 

 vTith the land well graded to a uniform slope and with the furrow 

 evenly made, it is all you should expect. If it will do it in fifteen, 

 it is fine ; if it takes twenty-four hours, it is good enough, pro- 

 vided you can have the water running for two days longer." 



This system is largely used for orchard cultivation in the 

 United States of America, and it is the one that seems to me most 

 adaptable for steep ground. The system, however, requires suit- 

 able soTT. In some soils the water does not spread sideways far 

 enough ; while in others, with furrows 3 feet apart, the moisture 

 will meet 2 feet below the surface in half a day and 6 inches below 

 In a day. The same writer quoted above states that, on his farm 

 with furrows 5 feet apart, he has seen the moisture at the surface 

 all the way between the ftirrows in cold cloudy weather. This, 

 however, must be exceptional, and I would not advise any one to 

 count on it doing it until he had made careful experiments. Where 



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