WATER SOILS. 479 



not appreciable at the end of 12 hours, but were as great as 1 em. after 

 24 hours and 2 cm. after 4S to 72 hours. The same ])eculiarity was 

 shown when an attempt was made to moisten the sterihzed soil, certain 

 well-defined zones remaining dry wliile the rest was thoroughly wet. 

 While the total nitrogen Avas not affected, a i)art of it was changed 

 into readily soluble (soluble in JICl, sp. gr. 1.02G) forms by sterilization 

 of the soil. The amount so changed was increased by wetting the soil 

 previous to sterilizing. Some of the transformed nitrogen was in very 

 unstable condition and was easily driven off as gas. 



It was observed in the pot experiments carried out that there was a 

 loss of nitrogen in the sterilized soil whether it was subsequently inoc- 

 ulated with soil extract or not, although the loss was generally less in 

 the latter case. The same was true in case of inoculated soils not 

 bearing plants, while the uninoculated soils in no case showed a loss 

 and in some instances a small gaiu. 



The amount of water-soluble organic matter was increased almost 

 three times in the sterilized soil, and the more vigorous growth of 

 plants in the sterilized soil is thus, in part, explained. 



Decomposition of vegetable matter in the presence of -water 

 and soil, E. Breal [Ann. Agron., ^>^ (1^96), Xo. 8, pp. 362-375.)— Tlxa 

 character of the organisms found in infusions of dead plants is briefly 

 discussed and investigations on the formation of ammonia by these 

 organisms from nitrogenous matter and on their influence upon the 

 nitrifying organisms are reported, together with a description of the 

 methods used in determining anmioniacal and nitric nitrogen. 



The character of these investigations and the principal results 

 obtained are shown in the following summary: 



Infusions of dead plants contain numerous organisms which attack 

 organic matter producing ammonia from nitrogenous matter. 



Their activity is checked when the ammonia becomes too abundant, 

 the highest amount observed in such cases being 0.2 gm. ammoniacal 

 nitrogen i^er liter. 



If the infusion contains organisms which destroy ammonia the latter 

 may continue to be formed. This is the case when the nitrifying 

 organism is present. Passing a current of air through tlie medium 

 greatly accelerates nitrification, and as a consequence the lU'oduction 

 of ammonia. 



Similar results are obtained when a lump of soil is moistened with 

 the infusion. At the surface ammonia disappears and nitric nitrogen 

 takes its place. In the interior ammonia accumulates because the nitri- 

 fying ferment cannot act there, a part of the nitric nitrogen originally 

 jiresent being reduced. 



A soil treated with an infusion containing organisms which produce 

 ammonia is likely to undergo nitrification more ra])idly than one not so 

 treated. Unusual activity of the nitrifying feriuent seems to be excited 

 under this condition. 



