REVIEW OF THE BOOK 305 



nitrogen is and what its sources are. What is ammonia? Nitric 

 acid? Nitrate? What is the relation of humus to nitrogen? What 

 is nitrification? How is it brought about? Is the nitrogen of the 

 atmosphere used by plants? If so, through what parts of the 

 plants is it taken up? How may we add commercial nitrogen 

 to the soil? 



What is the chief office of phosphoric acid? What crops use 

 liberally of it? What are sources of phosphoric acid? What is 

 meant by the term phosphate? What is an acid phosphate? 

 Superphosphate (143aj? Explain the relationships of phosphoric 

 acid to lime. What is a "reverted" phosphate? In what forms 

 are the phosphates found in commercial fertilizers? 



What is the office of potash? What are the sources of supply? 

 Whence came the commercial potash salts? Explain what 

 muriate and sulfate of potash are. 



What is an amendment? Give examples. How does an 

 amendment affect the soil? What effect may lime have on landf 

 In what form may it be applied? What do you understand by an 

 acid? Alkali? How many substances may be tested with regard 

 to acidity or alkalinity (153a1? Make the test with vinegar and 

 with lye. 



What is a commercial fertilizer? What is meant by a "com- 

 plete" fertilizer? What is meant by "guaranteed analysis?" 

 What is meant by the "brand?" What are the relative com- 

 mercial values of nitrogen, phosphoric acid and potash? Figure 

 out the commercial or estimated value of a ton of commercial 

 fertilizer when the guaranteed analysis is given. How may you 

 determine what is the value of commercial fertilizer? 



Would you advise using a complete fertilizer, or only one of 

 the fertilizing elements? Explain under what conditions. In 

 what kind of crops is nitrogen chiefly needed? Is there danger of 

 losing nitrogen from the soil? Do potash and phosphoric acid 

 tend to leach out as rapidly as nitrogen? In what soils is leach- 

 ing least pronounced? When are fertilizers applied, before or 

 after fitting the land? Explain the six conditions that govprn 

 the application of commercial fertilizers dfiS 1 . Can definite rules 

 be given for the application of such fertilizers? Why? 



