o2 ELEMENTS OF AGRICULTURE 



dry sand and notice how quickly it runs through, and how soon the 

 surface of the sand dries out. Treat some ordinary clay in the same 

 way and notice how differently it behaves. Mix the sand and clay 

 in varying proportions and find the proportions of each required to 

 furnish a mixture resembling the soils in your neighborhood. 



Questions 



1. Of what two kinds of matter besides water are soils 

 made up? 2. The organic matter in soils comes from what 

 two sources? 3. What elements make up the organic mat- 

 ter of soils? 4. What causes the decay of organic matter 

 in soils, and what substance is- produced by this decay? 

 5.. Why is it that frozen meat or vegetables keep so well? 

 6. Why is it that smoked or dried meats keep? 7. Why is 

 it that canned meats keep? 8. From what source is the 

 mineral matter of soils derived? 9. Name the three prin- 

 cipal constituents of soil. 10. Of what two elements is sand 

 made up? 11. What are large rocks made up of these two 

 elements called? 12. How is sand formed? 13. How does 

 clay behave when wet? 14. How would figures moulded 

 of wet sand behave when dry? 



