52 BOARD OF AGRICULTURE. 



geroiis as it would be to use nitrates in sucli a way. It is probably 

 advisable, however, to apply both forms of nitrogen in the spring. 



Dried blood, dried fish, meat scraps, and all animal substances con- 

 tain nitrogen in the organic forms in which it was built up in the 

 animal bodj'. When in such combinations it cannot serve as plant 

 food until a certain amount of oxidation or decomposition has taken 

 place. The various organic substances in the market differ very 

 much in the ease and rapidit}' with which the}' decompose and ren- 

 der available their nitrogen in the form of ammonia or nitric acid. 

 This transformation takes place rapidly with dried blood, fish and 

 meat, but slowly with hair, horn and leather waste. This iniport- 

 ;ant difference has an effect upon the price and upon the methods of 

 using such nitrogenous fei-tilizei'S. Such materials as horn dust, 

 leather waste, &c., would be of value to a crop if applied to the 

 soil long enough before the crop is grown, so that considerable 

 decomposition could be effected ; so that while it may not be an 

 incorrect practice to manure a piece of land with dried blood just 

 before it is sown to wheat, any substance resembling horn should 

 liave been applied some months previous. A very good method of 

 effecting the decomposition of animal substances that do not readily 

 pass through such a process is to compost them. By this means 

 their manurial value is more quickly and profitably utilized. INIore 

 or less phosphoric acid is contained in the above mentioned organic 

 manures in the insoluble form, which becomes slowly available. In 

 iicidulated fish the phosphoric acid is to an extent soluble as in a 

 superphosphate. Nitrogen in the organic form varies in price accord- 

 ing to the substance containing it, costing in fish scraps and horn 

 only three-fourths what it does in dried blood and meat. In an}'' 

 case a finely powdered fertilizer of this class would in justice bear 

 a higher price than one very coarse. Certainly the agricultural 

 value is increased by fineness of division. 



Superphosphates contain phosphoric acid as their principal ingre- 

 dient. They are manufactured by treating some form of bone or 

 phosphatic rock with oil of vitriol. Part of the phosphoric acid is 

 thus rendered soluble in water, the amount of this depending upon 

 the amount of oil of vitriol used. A portion of the bone or rock 

 are not acted upon, but this amount need be very small. The larger 

 part should have its phosphoric acid rendered soluble. Besides 

 the *' soluble" and " nnsolul)le" forms of ingredients, we have iri 

 nearly all superphosphates a form called "reverted." This name 



