678 ABSTRACTS 



cicola, inoculation is eminently desirable and that, even where the 

 organisms are present in limited numbers, the addition of larger num- 

 bers may be profitable. 



A marked difference in the quality of the different commercial cul- 

 tures for soil inoculation was noted, as was also apparent with the 

 inoculated soils employed. The variation was not greater with the 

 soils than with the commercial cultures. — Z. N. 



The Oxidation of Sulfur in Soils as a Means of Increasing the Availa- 

 bility of Mineral Phosphates. J. G. Lipman, H. C. McLean and 

 H. C. Lint. Soil Science, 1916, 1, 533-539. 



Environmental conditions play an important role in the activities 

 of sulfur oxidizing microorganisms. In soils containing sulfofying 

 bacteria under favorable conditions for their development elementary 

 sulfur is readily oxidized. Besides an abundant supply of oxygen, 

 moisture and the amount and quality of the organic matter are fac- 

 tors of direct significance. Moreover, the numbers and physiological 

 eflticiency of the organisms themselves are always of prime importance. 

 A strong analogy is shown between nitrification and sulfofication. 

 The oxidation of sulfur in soils by bacteria may lead to the accumula- 

 tion of large quantities of sulfuric acid, which in turn readily reacts 

 with basic substances, e.g., tri-calcic phosphate; this may then fur- 

 nish available phosphoric acid to crops. 



Compost heaps as well as cultivated fields may be so treated as to 

 provide a congenial environment for sulfofying bacteria and thus may 

 be utilized for the production of available phosphoric acid out of in- 

 soluble phosphates. — Z. N. 



Bacteriological Studies of a Soil Subjected to Different Systems of Crop- 

 ping for Twenty-five Years. P. L. Gainey and W. W. Gibbs. J. 

 Agr. Res., 1916, 6, 953-975. 



This is a report of investigations of various soil plats that had been 

 under the same system of cropping for twenty-five years, some under 

 continuous cropping, some in rotation. The tests made are: number 

 of bacteria developing on plates, ammonifying and nitrifying powers. 

 The writers conclude: 



"The soil under continuous corn and wheat contains, in the absence 

 of any additions of fertilizers or manure, relatively low numbers of 

 bacteria. In the presence of manure, continuous corn and wheat 



soil contain relatively high numbers 



"The agricultural practices under study .... produced no 

 appreciable effect upon the ability of the soil and its organic life to 

 liberate ammonia from cottonseed meal. 



"The ability of the soil complex to oxidize ammonia nitrogen to 

 nitrate nitrogen has been materially altered by the methods under 



study Continuous corn and wheat with no additions of 



manure or chemicals have brought about a relative low oxidizing 



