Power of Soil to Absorb Moisture from the Air 



Dry soil will absorb moisture from air in varying quantities, the 

 amount depending upon the character of the soil. This moisture, 

 known as hygroscopic water, enters the seed-bed and is beneficial to 

 plants if the ground is so thoroughly drained that air can freely circulate 

 through it. As the air passes through the soil, the moisture adheres to 

 the particles and in a limited way is beneficial. 



Schubler states that different soils possess this power in unequal 

 degrees. During a night of twelve hours and when the air is moist 

 one thousand pounds of perfectly dry 



Quarts Sand will gain pounds 



Calcaria Sand will gain 2 pounds 



Loam Soil will gain 21 pounds 



Clay Loam will gain 25 pounds 



Pure Agricultural Clay .27 pounds 



If the soil is of good tilth, thoroughly drained and contains an 

 abundance of humus, the amount of hygroscopic moisture absorbed 

 is increased. 



Size of Drain Tile to Use 



The size to use depends upon the length of the line, the fall, amount 

 of water to be carried away and the character of the soil. A one-inch 

 pipe carries one inch (circular measure) of water. A two-inch pipe 

 will carry four inches of water. A three-inch pipe will carry nine 

 inches and a four-inch pipe will carry sixteen inches of water. Thus 

 it will be seen that under the same conditions a four-inch pipe will 

 carry sixteen times as much water as a one-inch pipe, in fact it carries 

 more than that for the reason that friction is much less in a larger pipe 

 than in a small one. A drain tile eight inches in diameter with a fall 

 of three-tenths of a foot in one hundred feet will discharge 277,487 

 gallons of water in 24 hours. If a foot fall it will discharge 525,647 

 gallons during the same time. A four-inch drain pipe having three- 

 tenths of a foot fall in one hundred feet will discharge 43,697 gallons 

 in twenty-four hours and with a one-foot fall it will discharge 86,181 

 gallons. Therefore it can be seen from the above that the amount 

 of water a pipe will carry in a given time not only depends upon 

 the size of the pipe, but the fall which is a very important thing 

 to consider. 



Care should be taken to have the main tile large enough to carry off 

 the maximum flow without exhausting the capacity of the drain. If 

 the tile is not large enough it is apt to be undermined and disarranged. 

 The main can be made large at the outlet and gradually diminished 

 to the highest point using a reducer from time to time. At the junc- 

 tion where laterals join the drain tile, both main and laterals should 

 have a firm foundation and be well tamped on the sides and top. 



50 



