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PRACTICE 26 



Effect of Artificial Mulches upon Evaporation of Water 

 from Soils. 



Fill tubes as in preceding exercise to within one inch of top and 

 then fill the remaining part with material for mulch. Proceed as in 

 Practice 25. 



Tube 1. Check (filled to top with same kind of soil). 



Tube 2. One inch of sand. 



Tube 3. One inch of gravel. 



Tube 4. One inch of peat. 



Tube 5. One inch of sawdust or cut straw. 



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



Compute loss of water in tons per acre per week and tabulate 

 results. 



What will be the effect of these mulches on temperature? 



What is the principle of the growing of "Straw potatoes," i. e. 

 covered with straw and not cultivated? 



