36 



sedges, rushes and water grasses flourish it is certain that drainage 

 will be beneficial. The writer advises determining the average level 

 of the water table in all cases where there is doubt. This is easily done 

 by sinking holes in various parts of the field in question. The height 

 of the water in these holes indicates the level of the water table, and if 

 this, during the growing season, is found to be less than three and 

 one-half to four feet from the surface during considerable periods of 

 time, it is certain that the agricultural value of the field would be in- 

 creased by thorough drainage. 



Kinds of Drains. 

 Doubtless the first form of drain constructed by man was the open 

 ditch. Such ditches are in many cases still in use. The open ditch as 

 a channel for rapidly carrying off surface water is frequently desirable, 

 but as a means of thorough drainage is highly unsatisfactory. The 

 principal reasons are as follows : — 



1. The cost of construction is heavy. The sides must be sloped in 

 order that the ditch be reasonably permanent. The amount of earth 

 which must be removed is much greater than for under-drains of the 

 same depth. 



2. The cost of maintaining an open ditch is high. In many cases 

 the banks cave or wash and vegetation gradually obstructs the channel. 

 The open ditch to be satisfactory requires frequent attention. 



3. The open chtch requires too much land and is an obstruction to 



farm operations. 



Under drains. 



All of the different kinds of underdrains are free from many of the 

 faults which have been named in discussing the open ditch, and all of 

 them, therefore, have important advantages in operations designed for 

 the thorough drainage of land over open ditches. They are by no 

 means all of equal merit. The principal types of underdrains worthy of 

 consideration are the following: pole, box, stone and tile. 



Pole and Box Drains. — Both of these types of drains if properly 

 put in will do effective work for a time, but both are open to one 

 serious objection, — the material used in their construction is perish- 

 able. The principal item of cost in all of the different types of under- 

 drains is labor. It is therefore, in general, bad policy to employ in the 

 construction of drains any material which is perishable simply because 

 it costs less than something which is permanent. The pole or box 

 drain will last but a relatively short time on account of the decay of 

 the wood. The methods of constructing these drains, therefore, will 

 not be given. 



St07ie Drains. — The material used in the construction of these 

 drains is practically imperishable. In this respect, therefore, these 

 drains equal tile drains. In other important particulars, however, 

 they are inferior. The following are the principal points : — 



