CHAPTER XVIIl 



INFLUENCE OF SOIL ALKALI ON BACTERIA 



Soluble salts often accumulate in the soil of regions where the 

 annual rainfall is less than twenty inches. When the concentra- 

 tion of the salt becomes sufficient to be injurious to plants we 



Fig. 38. — Alkali soils. Produced by the addition of various soluble 



salts to a productive soil. 



have what is known as alkali soil. The trained eye readily recog- 

 nizes such a soil from its color and structure as well as from the 

 kind and condition of vegetation growing upon it. If the visible 

 vegetation is so profoundly modified, we involuntarily ask: How 

 does it influence the microflora.? Do the microorganisms disap- 

 pear from such a soil, or are they fewer in number.? Does alkali 

 soil contain a special microflora.? 



