246 TWO .METHODS OF FARM IRRIGATION. 



The strips must be carefully graded, and unless the ground' 

 has a long and easy slope requiring very little grading, and steeps 

 enough to ensure the required velocity for the water, they may be 

 more expensive and less eflficient than basins. In order not to 

 waste water, the surplus at the end of the strip should be collected 

 in a furrow and used on another piece of ground. 



These two systems of irrigation by flooding' differ In two im- 

 portant points — in true basin irrigation the ground is almost level, 

 and small basins, if filled quickly, are practically covered with- 

 standing water, while with the long strips a sheet of water is run- 

 over the surface, and there is no standing water. In deciding 

 whether to use flood irrigation or not, the following points should' 

 be considered : — 



(i). If the slope is suitable, flooding is the cheapest method for 

 handling large heads of water on large areas. 



(2). Where the soil is very porous, flooding is often the only 

 way to ensure quick and uniform wetting. 



(3). Where the sub-soil drainage is bad and the ground is 

 liable to become waterlogged, great care must be exercised' 

 in applying the water. 



(4). Where the slope is ton flat for the water to run in small 

 streams, flooding is often the only method for doing quick 

 work. 



(5). The rate at which your water is delivered (on a large irri- 

 gation canal this may be very important). 



The merits of irrigation by flooding may be stated very 

 shortly : — It is often the most convenient and most suitable 

 wethod, though not the best for results. An American irrigator 

 of over twenty-five years' experience, who has w-ritten a long 

 series of articles and is fully aware of the disadvantages of flooding 

 and the advantages of other methods, gives his own experience in- 

 the following words : — 



" I have a soil of several textures from near clay to the coarsest 

 gravel. In spring when it is windy much of the time, and in 

 summer when it is hot but rarely windy, I find it almost impos- 

 sible to get a decent stand of anything without flooding." 



He planted lucerne in the orthodox manner and it came up 

 verv badlv. The seeds were then drilled in on dry ground and :i 

 big head of water rushed over the whole patch with excellent 

 results. He goes on to say : — 



" I have found it the same in a greater or less degree with 

 about evervthing else. Even such a simple thing as a carrot T 

 could hardly raise at all with furrow irrigation ; but by thin 

 flooding I can raise at least 20 tons to the acre." 



These facts are given to show that every irrigator must adopt 

 the methods best suited to the conditions of his farm, and that 

 the beginner on a new piece of ground anywhere must study his 

 conditions and find out the most suitable methods for the special 

 crops he intends to grow. 



FURROW IRRIGATION'. 



I will now describe an entirely different svstem of irrigation, 

 one which, I think, will be largely employed in the future. As I 



