Lysimeter Experiments 



9 



THE LYSIMETERS AND THEIR TREATMENT 



Construction of the lysimeters 



The lysimeters are built of concrete. Each tank is 4 feet and 2 inches 

 square, with sides 4 feet and 3 inches deep and with a funnel-shaped bottom. 

 There are twenty-four tanks, arranged in two rows of twelve each. The 

 rows are 6 feet apart. Between the rows is a tunnel 6 feet wide, the 

 bottom of which is 10 feet below the top of the tanks. From the lowest 

 point in the bottom of each tank a drainpipe leads into the tunnel, where 

 receptacles are placed to catch the drainage water. 



The surface of the soil in the tanks is level with the surrounding soil 

 of the field. The walls of the tanks do not form the inside walls of the 



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Fig. 2. vertical section op tunnel, with sides and bottoms of tanks indicated 



BY dotted lines 



tunnel, but there is soil between these walls which is intended to reduce 

 conduction of heat from the tunnel to the soil of the tanks. 



Before soil was placed in the tanks the walls were covered with water- 

 proofing asphaltum to prevent the soil water from taking up any calcium 

 from the concrete. The tops of the tank walls are covered with sheet 

 iron, which extends down the sides 5 or 6 inches to protect the asphaltum 

 during tillage operations. 



The drainpipe is made of brass, fined with tin, and is 2 feet long and 

 2 inches in diameter. It is made large enough to permit of easy cleaning 

 and has no bend. The tube has a removable cap on the lower end, and 

 into the middle of this cap is fixed a steel rod which runs to within 

 4 inches of. the upper end of the tube, where it supports a perforated 



