332 SOILS AND FERTILIZERS 



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is fish-scrap fertilizer, and what is its comparative value ? 148. 

 What seed residues are used as fertilizer ? What is their value ? 

 149. What methods are employed to detect the presence of leather, 

 hair, and wool waste in fertilizers ? Why are these materials objec- 

 tionable ? 150. How may peat and muck be used as fertilizers? 

 151. What is sodium nitrate ? How is it used, and what is its value 

 as a fertilizer? 152. How does ammonium sulphate compare in 

 fertilizer value with nitrate of soda? What is calcium cyanamid? 

 153. What is the difference between the nitrogen content and the 

 ammonia content of fertilizers ? 



CHAPTERS V AND VI 



154. What is fixation ? What is absorption ? Give an illus- 

 tration. 155. To what is fixation due ? 156. What part does 

 humus take in fixation ? 157. Why do soils differ in fixative 

 power ? Why are nitrates not fixed ? Explain the fixation of 

 potash, phosphate, and ammonium compounds. 158. Why is fixa- 

 tion a desirable property of soils ? 159. Why is it necessary to 

 study the subject of fixation in the use of manures f ? Why is the 

 soil solution dependent upon the fixative power of the soil ? 160. 

 Why are farm manures variable in composition ? 161. What is 

 the distinction between the terms 'stable manure' and 'farmyard 

 manure' ? 162. About what per cent of nitrogen, phosphoric acid, 

 and potash is present in ordinary manure ? 163. Coarse fodders 

 cause an increase of what element in the manure ? 164. What 

 four factors influence the composition and value of manure ? 165. 

 What influence do absorbents have upon the composition of 

 manures ? 166. What advantages result from the use of peat and 

 muck as absorbents ? 167. Compare the value of manure produced 

 from clover with that from timothy hay. 168. How may the value 

 of manure be determined from the nature of the food consumed ? 

 169. To what extent is the fertility of the food returned in 

 the manure ? 170. Is much nitrogen added to the body during the 

 process of fattening ? 171. Explain the course of the nitrogen of 



