EXERCISE 5 



THE SOIL AS A SOURCE OF PLANT FOOD 



Statement. Mature seeds contain enough food to nourish the plant through the period of 

 germination and for a comparatively brief period thereafter. Soon, however, the growing plant must 

 begin to rely upon other sources for its food supply. One of these sources is the soil. 



Object. To show that the soil supplies a part of the food required by the plants for growth. 



Materials. Clean sand ; garden loam ; powdered rock or pieces of rock that may be powdered in 

 the classroom ; flowerpots ; rain water or distilled water ; seeds of corn, wheat, or beans. 



Directions. Take enough powdered rock, or powder enough rock material to fill a flowerpot, and 

 in it plant six beans or corn kernels. If these materials are not at hand, clean, fine sand may be used, 



Fig. 7. The soil's contribution to the harvest 



The scene on the left represents a waste of sand which is incapable of supporting much plant life. That on the right shows the rank 



growth of plants on a fertile soil 



first heating it in a shovel or iron pan until all of the material that will burn has been removed. Fill 

 another pot with garden loam and in it plant a like number of the same kind of kernels. Place both 

 pots where the plants will have a chance to grow and treat them exactly alike. Water both with 

 either distilled or rain water. Compare the plants as to the rate of growth at the end of a week and 

 each week thereafter until results are readily apparent. 



Questions. In which kind of material did the plants thrive best, and why ? What part of the sand 

 remained after it was heated? What material was destroyed by the heat? What part of the food of 

 the plant is supplied by the soil? In what condition does the growing plant take this material? 



References. Waters, H. J. Essentials of Agriculture, pp. 72-80. Ginn and Company. Lyon, Fippin, 

 Buckman. Soils, their Properties and Management, pp. 3-6. The Macmillan Company. Hopkins, C. G- 

 Soil Fertility and Permanent Agriculture, pp. 26-46. Ginn and Company. Stoddard, C. W. Chemistry 

 of Agriculture, pp. 26-27. Lea and Febiger. 



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