MANURES. THEIR SOURCES AND PREPARATION. 57 



. There are several other substances which, when they 

 can be obtained, should be carefully applied. Among 

 these, the most available are the offal of slaughtered ani- 

 mals, their carcasses, hair, and bristles, leather, refuse from 

 the tanners and shoemakers, woollen rags, fish, blood, etc. 

 All these contain the elements required by growing plants 

 in a very concentrated state. The hair, bristles, etc., may 

 be applied directly to any crop. These matters are very 

 powerful, and a small quantity will suffice. Slaughter- 

 house offal, and the carcasses of any animals that may 

 have died, should be buried deeply in a pit, with absorb- 

 ents beneath, and covered with muck or loam. In a year 

 it will become a most valuable manure. 



The following table from Boussingault gives a compre- 

 hensive view of the proportion of nitrogen contained in 

 the most common manures, and of their quality and equiv- 

 alents, referred to farm-yard dung as the standard. Thus 

 ten lbs. of fresh cotton-seed cake is equal in value to one 

 hundred lbs. of fresh or wet farm-yard dung, as far as the 

 nitrogen in each is concerned. To form a perfect table 

 of equivalents, the phosphates, potash, etc., must be also 

 taken into consideration. The ammonia merely indexes 

 the value. As a manure it is worth in the markets of the 

 world about 14 cents a pound, according to Prof. S. W. 

 Johnson. Insoluble phosphoric acid is valued by him at 

 4^- cts., and soluble phosphoric acid about 10J cents per 

 pound for application to ordinary crops. Potash is not 

 generally so deficient in soils as to be worth its market 

 price to be used as a manure, unless in the form of wood 

 ashes. Phosphoric acid in a soluble state is the only sub- 

 stance that approaches ammonia in money value for use as 

 a manure. 



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