THE MOISTURE IN THE SOIL 57 



rated or has been used by plants, if the soil is 

 in proper physical condition. Measures should 

 be adopted to prevent this moisture from be- 

 ing lost by evaporation. The most practical 

 and effective method is by establishing and 

 maintaining a surface mulch of soil. By fre- 

 quent use of implements of tillage, which loosen 

 the soil to a depth of two or three inches, this 

 mulch may be preserved and the moisture 

 saved. The drier and looser this mulch, the 

 more effective it is. This dry and loose surface 

 breaks the capillary connection between the air 

 and the moist under- soil, and has the effect of 

 interposing a foreign body between the atmos- 

 phere and the earth. A board or a blanket 

 laid on the earth has the same effect, and the 

 soil is moist beneath it. This soil -mulch should 

 be renewed, or repaired, in the growing season, 

 as often as it becomes hard or baked, by means 

 of shallow tillage. 



SUGGESTIONS ON CHAPTER III 



62a. To show that growing plants are constantly giving off 

 large quantities of water through their foliage, grow corn, beans 

 or squashes in rich soil in a flower- pot. Over the soil in the pot 

 should be placed a rubber or oiled cloth covering, so that no 

 moisture can come from this source. Then over the plant place 

 a glass bell -jar or a common fruit- jar, and notice how rapidly 

 tne moisture collects on the interior of the jar (Fig. 10). This 

 experiment may be conducted even better in the field. 



