14 



PRACTICE 21 



Determination of the Rate of Percolation of Water 

 Through Soils. 



Fill the tubes* provided for the purpose with the soils, without 

 compacting, to within a half inch of the overflow tube and place a 

 layer of coarse sand one half inch deep on top to prevent the dis- 

 turbance of the soil by the flowing water. 



Connect the tubes as in the figure by means of short rubber 

 tubes. Attach a to the water supply and b should lead to the waste 

 pipe or sink for taking off the overflow. Allow the water to flow 

 over the surface of the soil just fast enough to keep it constantly 

 flooded. Place flasks under the tubes c to catch any drainage water. 

 Note the time when water is turned on and also when percolation 

 begins. When the flow becomes constant, the quantity of water 

 draining from the soil in 30 minutes is determined. 



Use the same soils in the same way but compact them in the 

 usual manner. 



What application of this experiment do we see in farm practice? 



From this experiment, would it be advisable to plow deep? 



Would there be any advantage in fall plowing? 



What objection to a sandy soil does this experiment show? 



fr\ 



X 



= ^ 



*The tubes are of galvanized iron 2 inches inside diameter. The overflow tubes, 

 about % inch in diameter, are 1 inch from the top and the M inch bent drainage tube is 

 Vi inch from the bottom. 



