THE NATURE OF SOIL 43 



ways than by merely removing water. Thus these 

 two, the nitrogen-saving and the nitrogen- wasting 

 bacteria, are pitted against each other; the one is 

 a blessing to the soil, the other may be a detriment. 

 It is wise farming to encourage the growth of the 

 former by providing the conditions most favourable 

 for them thorough tillage and excellent drainage. 



Other Soil Bacteria. These two kinds of bac- 

 teria are but a very small part of the germ life of the 

 soil. Adametz has calculated that there are 

 50,000 germs of various kinds in a single gram of 

 fertile soil. Many are beneficial, most of them 

 are harmless, some are injurious. When the roots 

 and stubble of a certain crop decay in the soil, a 

 certain kind of "ferment," which is bacterial 

 growth, is produced. If the crop is grown for 

 several years on the same soil, after a while the soil 

 may become crowded with the particular kind of 

 ferment that the decay of the crop produces. The 

 result may be that eventually the soil will no longer 

 produce satisfactory crops of this plant, but it will 

 produce larger crops of some other. This is the 

 explanation, in many cases, of "clover-sick" and 

 "flax-sick" soils and other soils that fail to respond 

 as they used to. The practice of inoculating soils 

 with certain beneficial bacteria is discussed in 

 Chapter XII, with particular reference to legumi- 

 nous crops. 



The limits of the practical value of soil bacteriol- 

 ogy can only be surmised at this time ; but it seems 

 not improbable that the farmers of some future 

 generation may be able to inoculate their soils 

 with different beneficial bacteria and secure spe- 

 cific and valuable results, much as the butter 

 maker of to-day secures certain flavours with certain 

 cultures. The field of study opened before us by 



