36 BOTANY: PRINCIPLES AND PROBLEMS 



67. Which will absorb and hold a larger amount of water: Clay or 

 sand? Why? 



68. Will the rise of water by capillarity be higher in sand or in clay? 

 Why? 



69. Which is better for plant growth in a dry season, a clay soil or 

 a sandy one? Why? 



70. A layer of coarse gravel a few feet below the surface of the soil 

 makes the soil above it much drier than similar soil not underlain by 

 gravel. Why? 



71. Why does the surface of soil which has been perfectly dry during 

 the day often turn moist at night? 



72. Why is the surface of the soil in arid regions often caked with a 

 crust of salts? 



73. Why is a well-forested region apt to suffer less from drought than 

 one with no forests? 



74. Which will generally be colder, a soil with fine particles or one 

 with coarse? Why? 



75. A potted plant will dry out the soil in its pot very uniformly. 

 Explain. 



76. Is it better to water house plants by pouring water over the soil 

 or by letting the pots stand in water for a little while? Why? 



77. Explain exactly ivhy a mulch on the soil surface reduces loss of 

 water from the soil through evaporation. 



78. What basis in fact is there for the saying, "Water your garden 

 with a rake"? 



79. Why is it advisable to scratch over a garden with hoe or rake 

 as soon after a rain as the soil is workable? 



80. Why is it advisable to plow as early in the spring as the soil is 

 workable? 



81. Why is it important to water a plant before it is transplanted? 



82. Give three reasons for pressing the soil firmly about the roots 

 of a plant after it has been transplanted. 



83. After a plant has been transplanted, it is well to scratch over the 

 ground around it with a hoe or rake. Why? 



84. What advantage is gained by pressing down the soil above seods 

 after planting them? 



