56 



PRACTICE 27. 



Effect of Different Surfaces upon Evaporation. 



Fill all tubes with the same kind of soil to within one inch of top 

 by compacting. 



Fill one tube to the top with the same kind of soil and the others 

 with the material desired. 



No. 1. Check (filled to top with same kind of soil). 



No. 2. One inch of sand. 



No. 3. One inch of peat. 



No. 4. One inch of sawdust or cut straw. 



No. 5. One inch of gravel. 



No. 6. Pan of same area filled with water. 



The area of each tube is thirty-six square inches. 



Conduct this practice similar to preceding, computing loss of 

 water in tons per acre per week. Tabulate results. 



