146 SOILS AND FERTILIZERS 



brought under cultivation, so that it is not now so 

 essential to devise means for utilizing human excre- 

 ments as manure. 



THE PRESERVATION OF MANURE 



183. Leaching. Leaching of manure is the greatest 

 source of loss. Experiments by Roberts have shown 

 that when horse manure is thrown in a loose pile and 

 subjected to the joint action of leaching and weather- 

 ing it may lose in six months nearly 60 per cent, of 

 its most valuable fertilizing constituents. The tab- 

 ular results are as follows : l6 



April 25. Sept. 28. Loss. 



Lbs. Lbs. Per cent. 



Gross weight 4,000 1,73 57 



Nitrogen 19.60 7.79 60 



Phosphoric acid ... 14.80 7.79 47 



Potash 36.0 8.65 76 



Value per ton $2.80 $i .06 



Cow manure, on account of its more compact nature, 

 does not leach so readily as horse manure. A similar 

 experiment with cow manure, conducted at the same 

 time, showed the following losses : 



April 25. Sept 28. LOSS. 



Lbs. L,bs. Per cent. 



Gross weight 10,000 5,125 49 



Nitrogen 47 28 41 



Phosphoric acid 32 26 19 



Potash 48 44 8 



Value per ton .... $2.29 $1.60 



When mixed cow and horse manure was compacted 

 and " placed in a galvanized iron pan with a perfo- 

 rated bottom " for six months, the losses were as fol- 

 lows : 



