196 SCIENTIFIC AGRICULTURE. 



geeso, turkeys and ducks, are of less value than those of the 

 pigeon. 



Guano is the excrements of sea fowls, and is an earthy sub- 

 stance of a grayish brown color: it is mostly found in Africa 

 and South America. It is found on the islands and coasts of 

 those countries, in latitudes where the weather is so dry that 

 decomposition has proceeded slowly, and it has consequently 

 accumulated in large quantities. Guano is said to be efficacious 

 as a manure, applied to almost any crop : it is, however, accord- 

 ing to Johnston, more advantageous to root crops than to grain 

 or grass crops. It is conveniently applied as a top dressing, 

 mixed with gypsum, wood ashes or powdered charcoal. Two 

 or three hundred pounds to an acre is sufficient for a single 

 dressing. 



The urine of men and animals is the most valuable and the 

 most neglected of all manures. That of the cow and hog is 

 said to be more valuable, because it contains more solid soluble 

 matter than that of any other domestic animal. The efficacy 

 of urine as a manure is due to the large quantity of urea, 

 ammonia and phosphates, and consequently of nitrogen, which 

 it contains. Recent urine generally exerts an unfavorable 

 influence on growing vegetation ; it is most beneficially applied 

 after fermentation has fairly commenced, and before it reaches 

 the final stage of the process. (Johnston.) 



Decomposition is attended with a diminution of urea, and an 

 increase of ammonia. It is important that the urine collected 

 should be fermented in tightly covered cisterns to prevent the 

 escape of volatile matters : it has been proposed to add gyp- 

 sura, sulphate of iron, or sulphuric acid, to the fermenting 

 urine, in order to fix the ammonia; the mixture of vegetable 

 mold with it has been also recommended as equally effective 

 and more economical. The loss of manure in waste urine in 

 densely populated countries and large cities, is immense, as is 

 shown by the following calculation. 



