52 CHEMICAL MANUEES. 



LECTUEE FIFTH. 



/"^ ENTLEMEN : In practice, we consider 35,555 pounds of manure 

 \J the acre every two years as a good manuring. Our principal 

 object to-day being to compare manure with the chemical fertilizers, 

 we first ask how much 35,555 pounds of manure contains of the four 

 terms composing our complete fertilizer. 

 The reply is found in the following table : 



Azote 144 Ibs. 



Phosphoric acid 66 " 



Potash 133 " 



Lime 283 4 ' 



If it is true, as experience demonstrates, that manure owes all its 

 efficacy to these four products, you see that its active part is reduced 

 at least to one-fortieth of the whole mass. Moisture forms eighty 

 per cent, of manure, which reduces the solid part of 35,555 pounds 

 to 7111 pounds, of which the hydro-carbonate matter, whose utility 

 is .problematic, forms 3000 to 3552 pounds. 



You will not, then, be surprised if I add that with 2053 pounds of 

 chemical products one can compose a fertilizer of equivalent richness 

 to 35,555 pounds of manure. 



Here is the proof of it : 



Acid phosphate of lime 533 Ibs. 



Nitrate of potash 286 " 



Sulphate of ammonia 497 " 



Sulphate of lime 737 " 



Total 2053 " 



It is evident as regards facility of use, of spreading, economy of 

 transporting, etc., the advantage is with the chemical fertilizers. But 

 this is only a secondary point of view ; their true superiority rests on 

 other causes and is justified by other considerations. 



The azote of the manure is not immediately assimilable. It is 

 the contrary with the chemical fertilizer. This body in manure is in 

 the form of animal evacuations and partly putrefied litter, which 

 only acts favorably upon vegetation after having submitted to a de- 

 composition which completely changes its form ; azote is assimilable 

 'only after it is transformed into ammonia or nitrates. Now, this pre- 

 vious decomposition has, as a principal result, the loss of from thirty 

 to forty per cent, of the primitive azote of the manure, which is dis- 

 engaged in the air in the form of elementary azote. In the chemical 

 fertilizer the azote is, I repeat, immediately and entirely assimilable 

 its action, for this reason, being the more certain. 



Here is another still more important advantage in practice. 



You must certainly have remarked, in the formulae of fertilizers I 

 gave you in my last lecture, that the nature of these agents varied 



