INFLUENCE OF STABLE MANURE 



215 



finding in the soil a suitable habitat, and capable of using the soil 

 organic complexes as sources of energy or bringing about other 

 reactions more effectively than the organisms already present in the 

 soil. However, such microbes are only seldom present in animal 

 manures. 



The changes in the abundance of bacteria in soil as a result of 

 the addition of animal manure is shown in Table 51. There is an 

 appreciable increase in numbers following the application of fresh 

 manure; however, there is even a much greater effect as a result 

 of the treatment with sterile manure. This action of the sterile 

 manure results from the greater availability of the organic matter, 

 on account of the killing of the large numbers of bacteria in the 

 manure, as well as the modification of various organic constituents 

 during the sterihzation process. 



TABLE 51 



Influence of Manure (Applied at Rate of Ten Tons per Acre) on 

 Number of Bacteria in a Loam Soil (from Temple) 



The increase in the number of microbes following the addition 

 of stable manure to the soil may be considered to consist of several 

 steps. At first there is a decided increase in the abundance of 

 bacteria in the soil, due to the actual introduction of the bacteria 

 in the manure. This is soon followed by a drop in the number of 

 these organisms and by a rapid increase of the bacteria and fungi 

 of the soil itself, especially those organisms that use the constitu- 

 ents of the manure as sources of energy. Frequently there is a 

 sequence of organisms depending upon the nature of the manure 

 and the soil conditions. This sequence can be illustrated by con- 



