TILE DRAINAGE 23 



worked a few days earlier in the spring and can be cul- 

 tivated sooner after every heavy rain than an undrained 

 one. The matter of a few days in the length of the season 

 is a very important consideration for New England condi- 

 tions, as it frequently means the success or failure with 

 many crops. 



A fifth and very important effect of drainage is to in- 

 crease the available soil moisture. On first thought one 

 would say that the amount of soil moisture would be less- 

 ened, but let us see. When a plant must grow in a soil 

 which contains a surplus of water nearly to the surface, it 

 is forced to develop a shallow root system because the roots 

 cannot penetrate where all the spaces are filled with water. 

 The moisture in this shallow zone of root growth will soon 

 be used up and the soil become dry. This layer of dry 

 soil will then retard the capillary rise of water from be- 

 low and the plant will suffer in consequence. On the 

 other hand, if the soil is drained and the surplus water is 

 lowered the roots can develop deeper and thus have a 

 larger area from which to draw their moisture. Besides 

 this, a drained soil partakes of the nature of a sponge and 

 will the more readily absorb and hold the water which 

 falls as rain in a condition available for the plants. 



SIZE OF TILE AND FALL OF DRAINS. 



The size of the main drain will depend upon its fall and 

 the area which it drains. The greater the fall the smaller 

 may be the tile. If the fall is doubled the carrying ca- 

 pacity is increased about one third. A four-inch main 

 will suffice for most ordinary systems where not more than 

 ten or twelve acres are to be drained. If twenty or thirty 

 acres are to be drained into one main it should be five or 

 six inches in diameter. Tile larger than necessary should 

 not be used, as the cost increases much faster proportion- 

 ally than the size of the tile; for example: Three-inch tile 

 may be listed at $25, four-inch at $45, five-inch at $75 and 

 six-inch at $100 per thousand. 



