192 ON GUANO, AND ITS COMPARATIVE MERITS. 



Art. XLIIL— on GUANO, AND ITS COMPARATIVE MERITS. 

 By Professor Johnston. 



[At the meeting of the Yorkshire Agricultural Society, held August 5, 

 two highly interesting and instructive lectures were given by Professor 

 Johnston on manures. The one delivered at the public breakfast elicited 

 many valuable observations from several members of the society giving 

 the results of their experience in the use of different kinds of manure. 

 To elicit such a discussion was the professed object of the address.] 



With regard to g-uano, it was well known it was derived 

 from a description of sea-fowl wliicli lived on fish, and which 

 was produced in g-reat abundance. If they fed some fowls 

 on the ordinary food, and others on fish, they would find 

 that the manure of the latter was more valuable than that 

 of the former. There was another fact with reg-ard to the 

 manure of birds g-enerally. It was well known that the 

 excrements of animals, of cows, horses, sheep, &c., consisted 

 of solids and liquids. In the solids were found the phos- 

 phates ; from the liquids ammonia was obtained, or at least 

 the nitrogen which formed ammonia on fermentation. Now, 

 in tlie excrements of the sea-fowl and other birds, the liquids 

 and the solids were ejected tog-ether, and consequently it 

 was more valuable. This was an important point. Hitherto 

 only the solid excrements of animals had been really at- 

 tended to ; but they did not contain all that the farmer 

 wanted ; they did not contain the ammonia and saline qua- 

 lities which the liquids carried off. It was not necessary 

 that he should say much on the theoretical advantages of 

 g'uano, nor was it of much importance to them ; but they 

 would find, from the market-value of its main constituents, in 

 what its advantages really consisted. Ammonia was the 

 principal fertilizing ingredient, and the price of that was from 

 30s. to 4:1. per ton. In guano there was 65 per cent, of 

 ammonia, and a large proportion of phosphate of lime. 

 These two articles constituted the great proportion of guano, 

 as well as the most valuable in the market. He had 

 already told them that the sea-fowl ejected in one excrement 

 both ammonia and the phosphates ; whilst in animal excre- 

 ments, the phosphate was contained in the solid and the 

 ammonia in liquid. He would draw attention to some of 

 the varieties of guano which had recently come into the 

 market, in order that they might compare them with those 

 which had already come into use. These varieties had been 



