July 24, 1914] 



SCIENCE 



141 



to the soil. A comparatively small amount of 

 work has been done on the power of soil- 

 inhabiting fungi to produce ammonia under 

 like conditions. Miintz and Coudon^ demon- 

 strated that the production of ammonia from 

 the organic matter in soils is a property com- 

 mon both to molds and to bacteria. It is 

 interesting to note that they used both bouillon 

 and one hundred gram portions of soil, with 

 manure added as culture media. In their in- 

 vestigations they used two pure cultures of 

 molds, Mucor racemosus and Fusarium Mu- 

 entzii. Later Marchal^ confirmed their results. 

 In a series of investigations which were 

 carried on for the purpose of determining the 

 effect of acid phosphate on the ammonification 

 of dried blood in soils, we observed that with 

 varying percentages of acid phosphate the 

 amount of ammonia accumulated in one partic- 

 ular type of soil increased with the increase of 

 acid phosphate from 0.25 per cent, to 2 per cent. 

 There was but a slight decrease of ammonia 

 in the soifreceiving 5 per cent, of acid phos- 

 phate. In fact, there was over one half more 

 ammonia accumulated in the soil containing 5 

 per cent, of acid phosphate than in the soil to 

 which no acid phosphate had been added. It 

 was also observed that there was a very heavy 

 growth of molds on all soil portions receiving 

 acid phosphate. Counts were made of bacteria 

 in the soil portions, and it was found that 

 there was a decrease from 240,000,000 bacteria 

 per gram of soil in the portions containing 0.5 

 per cent, of acid phosphate to 12,200,000 in the 

 soil portions receiving 5 per cent, of acid 

 phosphate. The opposite effect was noted in 

 using certain other soils. There was no appre- 

 ciable growth of molds in these soils, and the 

 amount of ammonia accumulation decreased 

 with increased quantities of acid phosphate. 

 This was exactly the opposite of what was to be 

 expected as several investigators have held that 

 molds use ammonia for the development of 

 their mycelium. From these results we were 

 led to conclude that there was either a modi- 

 fication in the character or number of ammo- 



1 Compt. Bend. Acad. Sci., Paris, 116 : 395. 

 1893. 



2 BuU. Aoad. Boy. Belgique, III., 25: 727. 1893. 



nifying bacteria present, or that it was due to 

 the a mm onifying power of the large number of 

 fungi present in this soil and that this activity 

 was stimulated by the addition of a large 

 quantity of acid phosphate. 



Several plates which showed a considerable 

 number of mold colonies were set aside to 

 allow further development. Various fungi 

 were separated into pure cultures. Of these 

 the commonest were Zygorhynchus Vuilleminii, 

 Rhizopus nigricans, and certain species of 

 Penicillium. To guard against possible con- 

 tamination of the plates by spores from the 

 air, these fungi were reinoculated into the 

 soil from which they were isolated. Their 

 growth in this medium determines their status 

 as soil-inhabiting fungi. The fungi so secured 

 include, in addition to those already named, 

 species of Alternaria, Aspergillus and Tricho- 

 derma and several species of Mucor. One 

 other species, Monilia sitopMla, was isolated 

 from soils, which had been heated to a high 

 temperature in the autoclave. 



As the decomposition of the nitrogenous 

 materials in soils is influenced to a certain 

 extent by their chemical and physical composi- 

 tion and by their reaction, two soil types were 

 used; one of these was a gravelly loam acid 

 soil, the other a red shale neutral soil. Identi- 

 cal methods were used in the ammonification 

 studies. One hundred gram quantities of 

 sterile soil were used. The " beaker method "^ 

 was employed. Dried blood and cotton seed 

 meal were used as sources of nitrogen, amounts 

 of these containing 155 mgs. of nitrogen were 

 used in each case. The cultures were incu- 

 bated at 20° C. for seven days, and the am- 

 monia determined. 



There was found to be a considerable differ- 

 ence in the power of the various soil fungi 

 studied to ammonify dried blood and cotton 

 seed meal in the soil; that is, in their ammoni- 

 fying efficiency. A comparison of all of these 

 fungi was made in the loam soil, using dried 

 blood as a source of nitrogen. In all cases 

 but one the addition of two grams of acid 

 phosphate increased the ammonifying effici- 



8]Sr. J. Experiment Station Eeport, 1908: 129. 



