132 FERTILIZERS 



are used to furnish green manure? 4. State five uses of lime. 

 .">. How can a farmer tell the need of lime? 6. What different 

 forms of lime have you seen ? 7. If a man desires to plant an acre 

 of potatoes, what fertilizer should he use ? 



II" Ml EXERCISES 



1. Hunt up all the fertilizer sacks you can find and copy the for- 

 mulas on them. Bring these formulas to school and compare them 

 with those brought to school by other students. 



2. Do you know of any farmers who mix their own fertilizers? 

 Does it pay ? 



3. Visit a limekiln and find out all you can about it ; then write 

 up a report on burning lime. 



4. Get the selling price of manure and of the commercial fertilizers. 

 Which does the greatest amount of good, considering cost? 



5. Keep a careful record of the cost and action of fertilizers used on 

 your father's farm. 



SUGGESTIONS 



1. A way of making the study of fertilizers very practical is to ask 

 the pupils to report their home experience on the kind of fertilizer 

 used and the crop yields. It is not so much, however, a question of 

 getting information that counts, as it is the carrying out of a few 

 simple ideas for improving farm practice. When possible, a little land 

 should be used by the pupils themselves for this work. 



2. Many interesting and instructive experiments can be made with 

 a bit of limestone. Pour hot vinegar on it : carbon dioxide, a com- 

 mon gas, escapes. Throw a piece in the stove, and even when cooled, 

 it may burn the fingers, because it has been changed to a weak alkali. 

 Place a bit of the burned stone in a glass of water and blow your 

 breath into the water through a straw ; the water turns milky, show- 

 ing that you exhale carbon dioxide. 



REFERENCES 



Soils and Fertilizers. Snyder. 

 Fertilizers. Voorhees. 

 Farming with Green Manures. Harlans. 

 Talks on Manures. Harris. 



