CROPS AND SOIL IMPROVEMENT 



Permanency Desired. The expense of under- 

 drainage demands care in every detail of the work. 

 The grade of the trenches should be carefully 

 tested. Every piece of tile should be examined. 

 The outlet should be guarded against displacement 

 or entrance by animals. A good plan is to lay 

 the last few pieces of tile in a close-fitting wooden 

 box, and to protect the end with iron rods placed 

 2 inches apart. 



If the drain is on a true grade, so that no silt 

 will collect, there need be no fear concerning its 

 continued efficiency, provided water does not run 

 in it all the time. If it carries the water from 

 springs continuously, plant-roots may fill it, and 

 tree roots are quite sure to do so when opportunity 

 offers. This is notably true in case of elms and 

 willows, but protection is afforded in such an in- 

 stance by closing the joints with cement. 



[246] 



