Grade. 

 Date. . 



(60) 



EXERCISE 23 



Value of Mulches in the Retention of Moisture 

 Purpose. — To determine the loss of water from the surface of a soil by 

 evaporation and the value of various mulches in preventing this loss. 

 A mulch is any material placed or created on 

 the surface of a soil to prevent evapora- 

 tion. It may be composed of loose soil 

 or it may be artificial material, such as 

 leaves, straw, etc. 



PLAN 



1. The cylinders (Fig. 17) will be filled with 



loam soil in a moist condition. 



2. Treat the surface of the soil in each tube 



according to the table. The artificial 

 mulch should be 3 inches deep in all 

 cases. Fill the outside jacket of the cyl- 

 inder with water. 



3. Weigh each cylinder daily and calculate 



the loss of water. Replace the water which has been lost by evap- 

 oration. 



Value of Mulches 



Fig. 17. — A good form of cylinder for 

 mulch experiments. Water may be added 

 from time to time by the side tube. 



