414 NATUEE AND PBOPEETIES OF SOILS 



substance. Marchal found that B, mycoides was also capable 

 of ammonifying casein, fibrin, legmnin, glntin, myosin, serin, 

 peptones, creatine, leucine, tyrosine, and asparagine, but 

 not urea. 



The following reactions may be cited as indicating the 

 changes that probably occur when albumin and urea undergo 

 ammonification : 



CtsHusNisSO,, + 77O2 =: 29HoO + 72CO2 + SO3 + I8NH3 

 Albumin 



CON.H, + 2H2O =: (NHJ2CO3 

 Urea 



While ammonification ^ seems to proceed to the best advan- 

 tage in a well-drained and aerated soil with plenty of active 

 basic material present, it will take place to some extent under 

 almost any condition, due to the great number of different or- 

 ganisms capable of accomplishing the change. In certain 

 soils, as shown by Eussell and Hutchinson ^ as well as by 

 other authors (see par. 211), protozoa may retard ammoni- 

 fication by feeding on the chief ammonia-producing organ- 

 isms. Such a condition is seldom serious in arable soils. 



* The ammonifying efficiency of a soil is usually determined by treat- 

 ing a 200-gram sample of fresh soil with cottonseed meal or dried blood 

 carrying 120 milligrams of nitrogen. The mixture is then incubated, 

 usually for seven days, at optimum temperature and moisture. The in- 

 crease in ammonia is taken as a measure of the ammonifying efficiency. 

 The artificial nature of the test detracts largely from its value. See 

 Temple, J. C, The Value of Ammomfication Tests; Ga. Agr. Exp. Sta., 

 Bui. 126, 1919. 



^RuSSell, B. J., and Darbishire, F. V., Oxidation in Soils and Its 

 delation to Productiveness. Fart 2. The Influence of Partial Steriliza- 

 tion; Jour. Agr. Sci., Vol. 2, pp. 305-326, 1907. 



Russell, E. J., and Hutchinson, H. B., The Effect of Partial Sterilisa- 

 tion of Soil on the Production of Plant Food; Jour. Agr. Sci., Vol. 3, 

 pp. 111-144, 1909, 



Russell, E. J., and Hutchinson, H. B., The Limitation of Bacterial 

 Nmnhers in Normal Soils and Its Consequences; Jour. Agr. Sci., Vol 

 5, pp. 152-221, 1903. 



Buddm, W., Partial Sterilisation of Soil l>y Volatile a7id Non>- 

 ^olatile Antiseptics; Jour. Agr. Sci., Vol. 6, pp. 417-451, 1914. 



