470 SOILS: PROFEMTIES AND MANAGEMENT 



nutrients in the soil, and to a decrease in the number of 

 denitrifying bacteria, which obviates loss of available 

 nitrogen through their action. 



Heinze/ working with soils treated with carbon bisul- 

 fide, and Pfeiffer, Frank, Friedlander, and Ehrenberg,^ 

 working with steamed soils, found that there was a large 

 fixation of nitrogen following these treatments. They 

 conclude that this is at least partly responsible for the 

 greater productiveness of the soils after the treatments 

 mentioned. 



389. Russell and Hutchinson's theory. — The next 

 comprehensive theory to be brought forward was one by 

 Russell and Hutchinson, who account for the increased 

 productiveness of soils partially sterilized, either by heat 

 or by volatile antiseptics, as due to the use by plants of 

 the ammonia, which, as had been shown by previous 

 investigators, accumulated in soils so treated by reason 

 of the stimulation given to the process of ammonification 

 and the depression of nitrification. They hold, further- 

 more, that the stimulation of ammonification is brought 

 about by the greatly increased numbers of bacteria in 

 the soil following the destruction of some larger organisms, 

 probably protozoa or allied forms, that normally interfere 

 with the activities of the ammonifying bacteria. Care- 

 ful experiments by these investigators have shown that 

 there is a much larger quantity of nitrogen in the combined 

 forms of ammonia and nitrates in partially sterilized 



^ Heinze, B. Eine Weitere Mitteilungen iiber den Schwefel- 

 koMensto:ffi und die CSs-Behandlung des Bodens. Centrlb. 

 f. Bakt., II, Band 18, Seite 56-74, 246-264, 462-470, 624-634, 

 790-798. 1907. 



^Pfeiffer, Th., Frank, L., Friedlander, K., and Ehrenberg, 

 P. Der Stiekstoffhaushalt des Aekerbodens. Mitt. d. Landw. 

 Inst. d. Konigl. Univ. Breslau, Band 4, Seite 715-851. 1909. 



