PRACTICE 18 



Power of Compact Soils to Retain Water 



Use same tubes and soils as in Practice 17 and run at, the same 

 time if possible. Prepare the tubes in the same way but compact by 

 letting the weight drop three times from the 12 inch mark upon each 

 measure of soil. Fill to the crease except peat and proceed as in 

 Pr&cticG 17. 



Calculate the percent of water retained, the weight of water per 

 cubic foot of soil using the apparent specific gravity found in Practice 

 9, and the acre inches of water for each soil. 



Which soil becomes wet on top first? Why? How does this cor- 

 respond with total pore space? Which soil is drained first? Why? 

 How does this correspond with total pore space? 



How does rolling effect the water-holding capacity of a soil? 



