Life in the Soil 131 



their work can be controlled by the exclusion of the air. 

 Experiments are recorded which show that they are capa- 

 ble of converting the nitrogen in urine completely into 

 ammonia which escaped into the air in twenty-four 

 hours, when air was freely admitted, while this escape 

 of ammonia was almost entirely prevented by the exclu- 

 sion of the air, though the nitrogen was still largely con- 

 verted into ammonia. 



The same changes occurred in the solid excrement, but 

 more slowly. This explains the value of keeping manure 

 in box stalls under the feet of animals that pack it down, 

 and thus keep the air excluded. We have heretofore 

 shown that this is one of the best means for preventing 

 loss from the manure. How rapidly these micro-organ- 

 isms work, is well shown by the rapidity with which this 

 packed manure heats and loses nitrogen when thrown 

 out in heaps and exposed to the air. Maerker, an emi- 

 nent German investigator, has found that the nitrogen, 

 in deep, stall-fed sheep manure, compared favorably with 

 that of sulphate of ammonia and nitrate of soda; while 

 ordinary barnyard manure, which contained denitrifying 

 organisms from previous bad treatment, either did not 

 give good results, or actually lowered the yield. 



Kainit has been found to be effective in checking the 

 formation of ammonia and superphosphate in preventing 

 its escape; and they also add valuable constituents to the 

 manure heap. While caustic lime will, if appHed to fer- 

 menting manure, drive off the ammonia, it has been found 

 that Ume, appHed to perfectly fresh manure, will not cause 

 this loss, and that the loss will be very small. But so 

 quickly does the work of the organisms begin, that, while 



