254 



Proceedings of Indiana Academy of Science 



In addition to the above treatment, each pot from 1 to 10 inclusive, 

 received green manure in the form of young rye plants, at the rate of 

 twelve tons per acre. 



These pots were placed in the rose house of the Purdue horticultural 

 greenhouses and planted to soybeans. Moisture and temperature con- 

 ditions were kept at optimum. 



Bacterial numbers were determined by plating with standard beef 

 extract agar and incubating fourteen days at room temperature, which 

 was about 20° C. 



The bacterial types were studied by su.b-culturing on each of the 

 following media : 



1. Beef extract agar slants. 



2. Beef extract bouillon. 



3. Beef extract gelatin stabs. 



4. Nitrate reduction solution. 



5. Dextrose fermentation tubes. 



6. Lactose fermentation tubes. 



7. Brom cresol purple milk. 



Each culture was also studied miscroscopically, noting shape, spore 

 formation and motility. 



TABLE 1. Bacterial Numbers, Millions per Gram of Soil. 



Plate counts were made at four different times as shown in Table 1. 

 While the applications of calcium caibonate exerted no appreciable effect 

 on bacterial numbers, the application of green manure greatly in- 

 creased the total count of bacteria. This is particularly true at the 

 date of the second sampling, four weeks after the experiment was 

 started, when decomposition of the green manure was progressing very 



