728 



PRINCIPLES OF SOIL MICROBIOLOGY 



incubated at optimum temperature and moisture conditions for 30 or 

 60 days, and the amount of cellulose decomposed in that period of time 

 were found to be 400 mgm., this would indicate that about 7 to 8 mgm. 

 of nitrogen had become available in that period of time. 



TABLE 79 



Influence of NaNOz upon the decomposition of cellulose, in the presence of CaCOi 



and minerals 



TABLE 80 

 Influence of different forms of nitrogen upon the decomposition of cellulose in soil 3 * 

 (1 per cent filter paper added to 1 kilogram of soil) 



NITROGEN SOURCE 



Control 



16 mgm. nitrogen, as manure (10 grams) 

 32 mgm. nitrogen, as manure (20 grams) 

 64 mgm. nitrogen, as manure (40 grams) 



32 mgm. nitrogen, as (NH^SCU 



16 mgm. nitrogen, as NH4NO3 



32 mgm. nitrogen, as NH4NO3 



CELLULOSE LEFT, PER CENT 



Tables 79 and 80 bring out the influence of nitrogen in different 

 forms upon the decomposition of cellulose in the soil. 



To measure the cellulose-decomposing power of the soil, three meth- 

 ods are recommended. 35 



85 Waksman, S. A., and Heukelekian, O. Microbiological analysis of soil as 

 an index of soil fertility. VIII. Decomposition of cellulose. Soil Sci., 17: 

 275-291. 1924. 



