FARM DRAINAGE AND IRRIGATION 219 



Farm Ditches. The size of the farm ditches will be determined by 

 the acreage of land irrigated by each, the fall in the ditches and the 

 amount of water that must be cared for in a unit of time. On uneven 

 land it is necessary to bridge over the depressions with levees or flumes. 

 The levee is usually the cheaper, but should be allowed to settle. It will 

 be subject to wash-outs during the first few years. 



Wooden flumes are more satisfactory, but wood soon decays when 

 used for this purpose. Metal or concrete pipes cost most, but are durable 

 and generally cheapest in the end. The method of constructing the farm 

 ditches depends on their size. Most of the work on them may be done 

 with the plow arid the V-crowder. The crowder makes a ditch with a 

 triangular bottom. This bottom becomes rounded by usage. It is 

 important that the ditch be made in the proper place at the outset. 

 The older the ditch, the more impervious its banks and bottom become 

 and the more satisfaction it 

 gives. Leaky ditches may 

 be greatly improved by pud- 

 dling the earth of the sides 

 and bottom. This may be 

 done by drawing off the 

 water and driving a flock of 

 sheep the length of the ditch 

 while it is muddy. Drag- 

 ging the bottom with a 

 brush harrow may be re- 

 sorted to for the same pur- 

 pose. 



On well-established 



ditches the chief items of maintenance are the removal of silt, weeds 

 and aquatic plants that may grow in them. 



Distributaries. These consist of small wooden, metal or rubber 

 tubes, imbedded in the bank of the ditch so that the water will pass 

 through the embankment and be uniformly distributed on the adjacent 

 land. These need not be permanent, but may be imbedded temporarily, 

 and moved from field to field as needed. Square boxes, made of lath cut 

 in half, are cheap, light and serve the purpose as well as more expensive 

 metal tubes. Being square and rough, they stay in the embankment 

 better than the smoother metal or rubber tubes. 



Small syphons of rubber hose are also used. These obviate the 

 necessity of disturbing the ditch bank. The chief objection to these is 

 the starting of the flow of water. 



Distributing the Water. The method of distribution will depend 

 on the slope of the land, the character of the soil and the kind of crop. 

 Level land is easily irrigated by flooding the whole surface. This method 



1 Courtesy of The Macmillan Company, N. \V From " Principles of Irrigation Practice," by Widtsoe. 



CANVAS DAM TO CHECK WATER. 1 



