378 



THE PRINCIPLES OF SOIL MANAGEMENT 



Experiments conducted by Roberts serve to show 

 the rate and extent of deterioration of manure in a region 

 having a rainfall of about twenty-eight inches in the six 

 months from spring until autumn, during which period 

 the tests were made. The loss arising from fermentation 

 and leaching combined was determined in these experi- 

 ments. 



Horse manure was lightly packed in a wooden box, 

 not water-tight, surrounded with manure, and left 

 exposed to the weather from March 30 to September 30. 

 Analyses made at the beginning of and at the end of the 

 experiment showed the following: 



Table LVII 



Gross weight . . 



Nitrogen 



Phosphoric acid 

 Potash 



April 25 



Pounds 



4,000.00 



19.60 



14.80 



36.00 



September 30 



Pounds 



1,730.00 



7.79 



7.79 



8.65 



Loss 



Per cent 

 57 

 60 

 47 

 76 



At the same time, cow manure was similarly treated, 



except that 300 pounds of gypsum were mixed with it. 



This, doubtless, protected some of the nitrogen, and the 



greater body of material would also decrease loss of all 



constituents. 



Table LVII I 



Gross weight . . 



Nitrogen 



Phosphoric acid 

 Potash 



April 25 



Pounds 



10,000 



47 



32 



48 



September 30 



Pounds 



5,125 



28 



26 



44 



Loss 



Per cent 



49 



41 



19 



8 



