594 SOILS: PROPERTIES AND MANAGEMENT 



tage of either handling the liquid and the solid together, 

 or pumping the liquid over the solid at intervals, is there- 

 fore apparent. 



The general changes in any manure pile can readily 

 be recapitulated. First is the aerobic action, with escape 

 of ammonia and carbon dioxide. Next the manure is 

 wetted, it compacts, and the slow, deep-seated decay 

 sets in with a simplification of some compounds, with 

 the production of acids, and with a gradual formation 

 of humic materials. As the manure becomes alternately 

 wet and dry, the two general processes may follow each 

 other in rapid succession, the anaerobic bacteria attack- 

 ing the complex materials, the aerobic affecting both the 

 complex and the simpler compounds. Carbon dioxide 

 is given off continuously during the process. 



498. Gases from manure. The changes in the 

 composition of the gases drawn from wet and compact 

 manure, as compared with those from the same pile dry 

 and open, are well shown from results by Deherain. 1 

 The pile in this experiment was about eight feet high : 



COMPOSITION OF GASES FKOM DRY AND MOIST MANURE 



1 Hall, A. D. Fertilizers and Manures, p. 188. New York. 1910. 



