TRANSFORMATION OF ORGANIC MATTER 



679 



given in figure 55, while the transformation of a typical protein in the 

 soil is given in figure 56. 23 



The decomposition of organic matter in the soil can be traced by 

 determining one or more of the products of the reaction, at a definite 

 set of environmental conditions, and with a definite knowledge of the 



Fig. 56. Decomposition of a complex protein in the soil by microorganisms 

 (Schreiner). 



nature of the organisms which are active. These methods can be classi- 

 fied into three groups. (1) Methods which are based upon measuring 

 the amount of total original organic matter decomposed or only of one 

 or more of its constituents, such as cellulose or pentosan. (2) Those 

 methods which are based upon measuring the accumulation of one of 



23 Schreiner, O. Changes in character, condition and amount of soil organic 

 matter. Jour. Amer. Soc. Agron., 18: 115-126. 1926. 



