ORGANIC MATTER 113 



Ammonification—During the processes of decay the proteins 

 are caused by the bacteria to take up water and albumoses result. 

 These are caused to take up more water and in some mysterious 

 way fall to pieces, and we have peptones. The process is repeated 

 and there results amino-acid. The amino-acids are oxidized and 

 ammonia results. Therefore, the production of ammonia by 

 microorganisms is known as ammonification. 



The speed with which it is produced in a soil is governed by the 

 following factors: (i) the microorganisms which are bringing 

 about this change, (2) the material to be ammonified and the 

 nature of the soil, (3) moisture, (4) aeration, and (5) reaction. 



Organisms Causing Ammonification. — Although it has been 

 known for a long time that small quantities of ammonia occur 

 in all arable soils, yet its formation was not known to be due to 

 bacteria until 1893 when Miintz and Coudon demonstrated that 

 ammonia is no longer produced in soil sterilized by heat. Follow- 

 ing this, they and other workers tested many bacteria, yeasts, and 

 molds and found that numerous organisms possess the power of 

 producing ammonia. Some of the organisms are aerobic, other 

 Laerobif Both bacteria and molds pLss the power to a high 

 degree. A few of the more active organisms are B, ?nycoideSy 

 Sarcina lutea^ B. subtilisy and Proteus vulgaris. One organism 

 may act best on one substance and in one soil, whereas another 

 organism may be at its maximum efiSciency in an entirely different 

 soil working on other material. As these organisms exist in soil 

 probably there is a division of labor. One rapidly splits the com- 

 plex proteins, others act on the albumoses, and still others act on 

 the amino-acids. Then there are bacteria which quickly break 

 down lirea with the formation of ammonia. This may often be 

 detected by its odor in a stable on a warm day. Although we thus 

 find a great variation in activity and substance on which the am- 

 monifiers act, yet they are all working in keeping with the gen- 

 eral scheme of things, — the working over of old discarded mate- 

 rial and rendering it suitable again to be used by plants and even- 

 tually by animals. The numbers in a soil vary, but probably from 

 10 to 25 per cent of the soil flora are active ammonifiers. 



