MICROBIOLOGICAL ANALYSIS OF SOIL 735 



direct correlation between the humus content of the soil and its cata- 

 lytic power. According to May and Gile, 45 the catalytic action of a soil 

 is a rough measure of the combined quantity of bacteria and organic 

 matter present. Surface soils were found 46 to be more active than 

 subsoils, more fertile soils are more active than infertile ones. 



Since inorganic soil constituents are also capable of liberating oxygen 

 from H 2 2 , Chouchack 47 used the difference between the oxygen formed 

 by normal soil and that formed by the same amount of sterilized soil 

 as an index of the biological activities. By treating the soil with 

 phosphates, potassium and nitrogen salts, then determining the increase 

 in catalytic action, reliable information can be obtained on the practical 

 value of such treatments. Osuga, 48 however, confirmed the previous 

 observations of Konig and associates that ferric oxide, manganese oxide 

 and humus show marked catalytic action. He suggested that these 

 substances may be the main constituents which react with the H2O2. 

 Bacterial effect in soil catalysis was believed to be small. In this 

 respect, he confirmed the earlier observations of Kappen 49 that the 

 catalytic action of the soil is due largely to the colloidal complexes of 

 the soil. 



The catalytic action of the soil is thus found 50 to be due to the inor-* 

 ganic constituents of the soil; to certain organic soil compounds, such 

 as benzol derivatives, and to the action of catalase formed by micro- 

 organisms in the soil. Although a correlation exists between the 

 catalytic action of the soil and the numbers of soil microorganisms as 

 well as soil productivity, the phenomenon is very complex and cannot 



" May, D. W., and Gile, P. L. The catalase of soils. Porto Rico Agr. Exp. 

 Sta. Circ. 9. 1909. 



46 Sullivan, M. X., and Reid, F. R. Studies in soil catalysis. Bur. of Soils. 

 U. S. Dept. Agr. Bui. 86. 1912. 



47 Chouchack, D. L'analyse du sol par les bact6ries. Compt. Rend. Acad. 

 Sci., 178: 1842^, 2001-2. 1924. 



48 Osuga, C. On the catalytic action of soil. Ber. Ohara. Inst. Agr. Invest. 

 Kuraschiki., 2: 197-218. 1922. 



49 Kappen, H. Die katalytische Kraft des Ackerbodens. Fiihling's landw. 

 Ztg., 62: 377-392. 1913; see also Smolik, L. Hydrogen-peroxide catalase of 

 marsh soils. Proc. Intern. Soc. Soil Sci., 1: 6-21. 1925; A detailed review of the 

 occurrence and action of catalase in general is given by Morgulis, 8. Die Kata- 

 lase. Ergebn. Physiol., 23: 308-367. 1924. 



60 Waksman, S. A., and Dubos, R. Microbiological analysis of soils as an 

 index of soil fertility. X. The catalytic power of the soil. Soil Sci., 22: 407-422. 

 1926. 



