COMPOSITION OF ANIMAL MANURES 369 



contains the following average percentages of the organic 

 matter, nitrogen and mineral substances originally 

 present in the food consumed: 



Per cent 



Organic matter 33.90 



Nitrogen 39.50 



Mineral substances 56.25 



In Robert's calculations, the value of the manure is 

 based entirely upon its content of nitrogen, phosphoric 

 acid and potash, valued at 15 cents, 7 cents and 4.5 cents, 

 respectively. It is difficult to get a true idea of the value 

 of animal manure, as its content of fertilizing substances 

 is only a part of its manurial value, of which its physical 

 and bacteriological effects upon the soil are extremely 

 important. 



Horse manure has the fibrous matter of the food less 

 well broken down than has cow manure, and this, with 

 its lower water content, produces a light, easily ferment- 

 able substance that readily loses its nitrogen, which 

 passes off as ammonium carbonate. The dry fermen- 

 tation, indicated by a whitish appearance of the interior 

 of the manure heap and a slight smoke, is the cause of 

 this loss. The values calculated for the excrement are 

 never realized in practice because of the losses that 

 occur between the stable and the field. To preserve 

 horse manure to the best advantage, it should be mixed 

 with cow manure, the wet, compact character of 

 which lessens the amount of fermentation by changing 

 the physical condition of the manure. 



239. Cow manure. A mature cow, given good feed, 

 will produce from 60 to 90 pounds of excrement daily. 



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