TRANSFORMATION OF MINERALS IN THE SOIL 



667 



may even form definite compounds with some of the constituents of 

 the soil organic matter. 65 The transformation of organic and inorganic 

 substances in the soil by microorganisms affects directly or indirectly 

 the solubility and condition of aluminum in the soil; the oxidation 

 of sulfur in the soil brings into solution considerable quantities of alu- 



per 100 cc. 



10 



15 



20 



25 



30 



Fig. 51. Influence of KH 2 P0 4 on the formation of ammonia from peptone by 

 bacteria (from Fred and Hart). 



minum, the same is true of the formation of nitrous and nitric acids 

 from ammonia in soils deficient in bases. 66 



Role of minerals in bacterial metabolism. The various minerals studied 

 here are more or less essential to the metabolism of microorganisms 



65 Niklas, 1912 (p. 644); Ostwald, W., and Steiner, A. Beitrage zur Kolloid- 

 chemie von Humussiiure und Torf. Kolloidchem. Beih., 21: 97-170. 1925; 

 Waksman, 1926 (p. 447). 



66 Further information on the transformation of aluminum in the soil is given 

 by'Stoklasa, 1922 (p. 646). 



