318 EXPERIMENT STATION RECORD. [Vol.40 



and biochemical activities which characterized the various soil layers. It Is 

 thought that methods devised for soil sampling for ordinary soil bacteriological 

 work have been based upon an erroneous assumption that the dangers from 

 contamination are considerable. "The soil flora in a given sample of soil 

 seem to be bo large, so characteristic, and so firmly established and adapted to 

 the conditions under which they are found that the introduction of relatively 

 small numbers of contaminating organisms into that sample is without per- 

 ceptible effect on the original flora as shown in ordinary tests on soils." 



Large bacterial numbers and well-marked bacteria] activities were observed 

 at relatively great depths in soils of the arid region, although the surface foot 

 of soil was by far the most active biochemically and was the most densely 

 populated. In some phases of bacterial activity the second foot approached or 

 equaled the first, while, as a rule, the soil layers from 2 to 6 ft. were nearly 

 uniform in bacterial population and activity. 



The importance of mold action in the soil. S. A. WAK8MAH (Soil Soi., (> 

 (l!)is>, No. J, pp. 187-155).— In this paper, a contribution from the New Jer- 

 sey Experiment stations, the author discusses in some detail the metabolism 

 of molds which are commonly found in the soil, basing bis observations and 

 conclusions upon the work of differeni Investigators, hut chiefly upon the re- 

 sults of his own studies. The points receiving consideration include the 

 occurrence of molds in the snii, nitrogen fixation, nitrification, ammonification, 

 decomposition of carbon compounds in the soil, utilization of nitrogen com- 

 pounds, enzym production by molds, the possible modification of soil reaction 

 by the action of molds, the effect of molds upon the mineral transformations in 

 the soil, ami the relation of soil fungi to plant dlj 



Summarizing, the author states that "molds have been isolated in large num- 

 bers from differeni cultivated and uncultivated soils, and the identity of many 

 genera and species isolated from widely different localities has been estab- 

 lished. The cultivated soils contain by far a smaller number of molds than they 

 do bacteria and Actinonivcetes. Molds live and produce mycelium in the soil, 

 and therefore take an active part in the transformation of some of the organic 

 anil Inorganic substances which are Important factors in the fertility of the 

 soil. The plate count of molds in the soil can not be taken as an indication of 

 the actual numbers of molds living in the soil. 



"The molds present in the soil, at least most of them, do not lix any atmos- 

 pheric nitrogen, and even where fixation was shown to be positive the quan- 

 tities are so small as to be negligible in the study of soil fertility problems. 

 .Molds do not seem to play any part in the process of nitrification. The molds 

 play an important role in the decomposition of organic matter witli the BUbse- 

 quent liberation of ammonia. The amount of ammonia produced depends not 

 only on the source of nitrogen, but also on the carbohydrates available. 



"The molds take an active part in the decomposition of the simple and com- 

 plex carbohydrates in the soil, with the production of carbon dioxld; this brings 

 about a mineralization of the organic matter winch is thus made available for 

 higher plants. The molds utilize very readily the nitrogen compounds usually 

 added to the soil in the form of different fertilizers and convert them into com- 

 plex body proteins, thus competing with the green plaids and exerting an in- 

 jurious effect upon soil fertility. This may be somewhat counterbalanced by 

 the fact thai some of the soluble nitrogen compounds are thus saved from loss 

 by drainage from the soil and that the fungus body undergoes autolysis, thus 

 liberating in a soluble form most of the nitrogen that it has assimilated, 



"The molds isolated from the soil produce a number of enz\ ms which may 

 help to bring about decomposition processes, which are Important t<> the upkeep 

 of the fertility of the soil. The production of acids by some molds in the soil 



