TILE DRAINAGE 109 



WHY ROOTS DO NOT USUALLY OBSTRUCT DRAINS. 



Because they do not wish to do so. in a well -constructed drain 

 there is ordinarily no inducement. A few days ago I took up a 

 joint of an old main to insert a new lateral, and examined closely. 

 There were plenty of wheat roots about the tile, and a few had 

 feebly entered the cracks. But finding no moisture and no soil or 

 " silt" in short, nothing but a dry, empty hole they had given 

 it up as a bad job, and literally backed out and gone again into 

 the soil for moisture. They concluded they couldn't "make" 

 any thing there, according to the doctrine, " Ex nihilo nihilftt"- 

 '* You can't make something out of nothing." And in well- 

 constructed drains in clay soil, or in any soil that is not ''springy," 

 this will, I think, be the ordinary result. At all events, the 

 drains on such soils do last many years, with no tendency to 

 stoppage from roots. There is no moisture in the drains to lure 

 the roots, except when there is too much moisture everywhere 

 else. 



When will roots obstruct drains? I answer: When there is 

 water or damp silt in the drains and dry ness in the soil. This 

 will occur in improperly constructed drains, or when there is 

 perennial water in the drains from springs or springy ground 

 higher up the slope, and dryness in the soil through which the 

 drains pass, and on which are gro \ying crops. Even in ordinarily 

 dry soils, with no running water in the tiles in summer, if there 

 are ; ' dips," or depressions, in the drain, water will stand confined 

 for some time after the flow ceases, and silt will lodge, and roots 

 will enter and help make the stoppage complete and permanent. 

 The remedy or, rather, preventive here is to construct the drain 

 on a true grade, and have no '' dips." In case of perennial water 

 in the tiles, the remedy is not so simple. If the soil through 

 which the water flows becomes itself dry, the roots will surely 

 seek the water in the tiles. How shall they be excluded, and yet 

 the water be admitted from the adjacent soil, as well as from the 

 spring or springy ground above? The only way I know is to use 

 soft, porous tiles, exclude all that have " pin-holes " in them, and 

 lay the joints in hydraulic cement. The water will enter the 

 pores of the tiles, but the roots can not. If any one doubts about 

 the water entering, let him lay out a few large, soft-burnt tiles in 

 a commencing shower, and see how they swallow the big drops 

 as soon as the latter fall. Or let him set such a tile on end in 

 piaster of Paris, or cement, on a board or plate; and when the 

 cement or plaster is hardened, fill the tile full of water. But it 

 must be quite soft- baked and porous, and such tiles are not so 

 durable, and should never, I think, be used except in case of 

 such danger from roots.* 



* NOTE. Sept. 18, 189J. This was written in 1880. I had not then (I 

 may as well confess) actually made the experiment of setting a soft-baked 

 tile on its (Mid in plaster of Paris and filling- it with water, but I took 



