1917] SOILS FEETILIZERS. 215 



Stations with garden, orchard, meadow, and forest soils, gravelly loam, a medium 

 loam containing 48 per cent iron, an adobe soil from Oregon, and different 

 California soils are reported to determine the numbers and activities of soil 

 fungi. 



It was found that the fungi found in all the soils studied represent a group of 

 organisms in numbers large enough to warrant a conclusion that they probably 

 play an important part in the fertility of the soil. No distinct difference was 

 observed between the species of fungi found in cultivated soils and those in 

 uncultivated soils, though each soil seemed to have a more or less character- 

 istic fungus flora ; for example, the cultivated orchard soil, has a great abun- 

 dance of Mucorales, while the forest uncultivated soil, has an abundance of 

 Penicillia and Trichodermfe. The numbers of fungi decreased rapidly with 

 depth, so that at 12 to 20 in. below the surface very few fungi were found, the 

 largest numbers occurring within the iipper 4 in. of soil. As to the species, no 

 distinct differences among the organisms were found with the different soil 

 depths, except that in the subsoils of most of the soils studied, Zygorhynchus 

 vuilleminii was found to be present, often as the only organism, when soil 

 was inoculated directly upon sterile medium. 



" Over 100 distinct species of fungi were isolated from the soil, belonging to 

 31 genera, many of the species being isolated from several of the different 

 soils. jNIany pathogenic fungi, such as different Fusaria, Alternaria, Aspergilli, 

 Coniothyrium, and others, have been isolated from the soil. . . . 



" The study of the physiological activities of the fungi pointed out the fact that 

 they do not play a very great, if any, part in the fixation of atmospheric nitro- 

 gen, but they do prove to be able to decompose organic matter rapidly and liber- 

 ate ammonia, under laboratory conditions. Jlany of them prove to be strong 

 decomposers of cellulose, though fewer of them hydrolize starch." 



A list of 125 references to literature bearing on the subject is appended. 



Azotobacter in Hawaiian soils, P. S. Buegess {Soil ScL, 2 (1916), 2fo. 2, pp. 

 183-192). — Experiments conducted at the Hawaiian Sugar Planters' Station 

 on the azotobacter content of 30 sugar cane soils from the islands of Oahu, 

 Hawaii, Maui, and Kauai, as indicated by their ability to fix nitrogen in man- 

 nite solutions are reported. 



Only 5 soUs were noted which failed to show azotobacter growth in so- 

 lutions. " In these cultures some fixation is recorded which indicates that 

 probably certain Clostridium forms are also fairly prevalent here." Four dif- 

 ferent forms of Azotobacter were isolated in pure culture, namely, A. chroo- 

 coccuni var., A. vinelandii n. var.? A. vinelandii var., and " B 29? ". 



Two references to literature bearing on the subject are appended. 



Environmental factors influencing the activity of soil fungi, D. A. Colkman 

 (Soil Sci., 2 (1916), No. 1, pp. 1-65, figs. iO).— Experiments conducted at Rut- 

 gers College with sandy loam and clay loam soils on the influence of organic 

 matter in the form of dried blood, cottonseed meal, soy-bean meal, vetch, and 

 rye ; of mechanical and chemical composition of the soil, moisture, and temper- 

 ature on the activity of soil fungi ; and experiments on the associative action 

 of soil fungi and soil bacteria are reported. It was found that the type of soil, 

 the quality of the organic matter, definite combinations of soil and organic mat- 

 ter, mechanical composition, and moisture content of soil are important factors 

 in regulating the activities of the organisms tested. 



The effect of time and depth of cultivating a wheat seed bed upon bac- 

 terial activity in the soil, P. L. Gainey (Soil Sci., 2 (1916), No. 2, pp. 193-204, 

 figs. 4)- — This article reports studies conducted at the Kansas Experiment Sta- 

 tion on nitrate and ammonia formation in soil, described in a report of previous 

 experiments by Call (E. S. R., 33, p. 217) on the effects of different methods 



