MANURES AND FERTILIZERS. 123 



will be surprising to many that tankage, a popular 

 nitrogenous fertilizer, gave up only forty per cent of its 

 nitrogen to crops in two years, thus standing in avail- 

 ability at fifty-nine, compared to nitrate of soda as one 

 hundred. 



Ammonia should not be confused with nitrogen. 

 Seventeen parts of ammonia contain fourteen parts of 

 nitrogen. Oftentimes manufacturers give the equiv- 

 alent proportion of ammonia, instead of the actual 

 amount of nitrogen, for the same reason that the term 

 phosphate of lime is used because it looks bigger. 

 Expressed in decimals, one part of ammonia contains 

 0.8235 of nitrogen. Thus, if a fertilizer contains five per 

 cent (or one hundred pounds per ton) of ammonia, the 

 nitrogen is only 4.12 per cent, or eighty-two and one- 

 third pounds. For quick calculation, ammonia can be 

 reckoned to contain four-fifths of nitrogen, and by de- 

 ducting one-fifth from the quantity of ammonia, the 

 amount of nitrogen actually present will be reached 

 quite closely. 



Cottonseed Meal. Of all the sources of nitrogen, 

 the most popular is cottonseed meal. As a concentrated 

 food for cattle its value is highly appreciated, and it is 

 one of the leading meals for milch cattle. But, apart 

 from the tobacco crop, it is not much used as a fertilizer 

 at the North. In the southern States cottonseed, fer- 

 mented, to destroy the germ, has long been a favorite 

 dressing for cotton fields, especially when mixed with 

 plain superphosphate and kainit. Of recent years the 

 practice of selling the seed to oil mills, and buying back 

 the dry meal, has gradually spread, and in sections 

 adjacent to railroads in these States, large quantities of 

 meal are annually consumed for fertilizing purposes. 



Iii the preparation of the meal, the cottonseed, 

 which is about the size of a coffee bean, is taken as it 

 comes from the gin, covered with a short fuzz of cotton 



