56 Microbiological Population of the Soil 



tors that influence the bacteria. Among the various counts reported, 

 the following may serve as an example: the flagellates ranged from 

 100,000 to 1,000,000 per gram, the amoebae from 50,000 to 500,000, 

 and the cfliates from 50 to 1,000 per gram. Plots of soil treated with 

 manure and with organic fertilizers had much larger numbers of 

 amoebae than untreated plots, as shown in Table 9, 



Table 9. Influenxe of Soil Fertilizatiox upox the Xumbers of Amoebae ix 



Soils (from Singh) 



The distribution of algae in the soil is controlled largely by hu- 

 midity and by depth of soil. Although the subterranean numbers 

 of algae appear to bear no relation to the abundance of carbon and 

 nitrogen compounds in the soil, manuring was found to have a de- 

 cided influence upon the development of specific types. The effect 

 of manure upon the distribution of algae in different depths of soil 

 is illustrated in Table 10. 



Table 10. Ixfluence of Maxure axd Soil Depth upox the Distributiox of 

 Algae ix Soil (from Bristol-Roach) 



Earthworms and nematodes are also widely distributed in the soil. 

 A typical enumeration of nematodes in different soils is given in 

 Table 11. 



