SPECIAL FARM TOPICS 287 



ditches or laterals are located along the best routes. These form a 

 network of channels which cut up the field into small strips, which 

 are usually from 50 to 100 or more feet in width. Custom differs 

 as to the direction of these field ditches. Sometimes they extend 

 down the steepest slope of the field regardless of the fall, at other 

 times they follow grade lines and extend from the head ditch in 

 more or less curved lines across the field. 



In preparing a field for this method it is first plowed and har- 

 rowed and then graded. When the ditches extend down the steep- 

 est slope of the field they are located by eye, but when they are 

 located on grade lines some kind of a surveying instrument is fre- 

 quently required to establish the grades. A suitable fall for these 

 small channels is one-half to three-fourths inch to the rod. (Y. B. 

 1909.) 



In cases where the extra expense is warranted, small wooden 

 head gates may be used in diverting the flow from the head lateral. 

 Quite as good results can be secured, however, by the use of the can- 

 vas dam, which also can be used for turning water from field lat- 

 erals. This dam consists of a large piece of canvas 6 to 10 feet 

 square, one edge of which is fastened to a pole or iron rod sufficiently 

 long to reach across the lateral and strong enough to support the 

 canvas against the pressure of the water. Being light, the dam can 

 be carried from one part of the field to another. It is inexpensive, 

 and is made often of scrap material. An old wagon sheet or the 

 carrier apron of an old binder or header will do for the canvas sheet 

 and any strip of tough wood will do for the crosspiece. Under cer- 

 tain conditions a wrought-iron rod is preferable to the wooden cross- 

 piece, for if it is desired to turn out only a portion of the stream, the 

 rod may be bent downward and the remainder of the stream allowed 

 to flow on. 



The advantages and disadvantages of the flooding method may 

 be summed up as follows : The principal advantages are : The cost 

 of preparing the land is comparatively small, aside from the gen- 

 eral turning up of the field's surface, there is no need of disturbing 

 the surface soil; it readily adapts itself to the delivery of water in 

 continuous flow. The principal disadvantages are: The amount of 

 labor required to handle the water is large ; one man can not thor- 

 oughly irrigate on an average more than 3 acres in 10 hours ; in all 

 grain crops the field ditches have to be renewed each spring; it may 

 be difficult to distribute the water evenly over the surface. (Ex. S. 

 Circ. 67.) 



Furrow Irrigation. Nearly all crops that are planted in rows 

 and cultivated are irrigated by means of furrows. This applies to 

 such crops as potatoes, sugar beets, corn, vegetables, and fruit. The 

 ground is first plowed, leveled, and graded in much the same way 

 as that just described. The field is then divided so that each part 

 can be readily watered from a head ditch. The distance between 

 any two consecutive head ditches depends chiefly on the soil. In 

 porous, sandy soils furrows should not be more than 300 feet 

 long. In soils which absorb water less freely they may be 400 to 



