EXERCISE A-14. TO SHOW THE EFFECT OF SOIL AIR 



UPON PLANT GROWTH. 



Equipment: Two tumblers, or quart cans; several 

 grains of corn. 



Method: Fill two tumblers within a half inch of the 

 top with rich soil. Plant in each three kernels of corn. 

 Water tumbler No. 1 only enough each day to keep the 

 soil moist. Keep water in the second tumbler so that it 

 stands a little above the surface of the soil. Fill in the 

 following blanks: 



What kept the corn in one tumbler from growing as 

 well as that in the other? W^hat became of the air in the 

 soil in tumbler No. 2? 



Discussion: For the best growth of crops the space 

 not occupied by soil particles should be divided equally 

 between air and water. If this space becomes entirely 

 filled with water, crops will not thrive, since their roots 

 will not be able to get the air necessary for plant growth. 



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