1!>201 SOILS — FERTILIZERS. 625 



668-609). — Exporlnionts confluctod by the Bureau of Soils of the U. S. Depart- 

 ment of Agriculture to determine the nature of the salts which are crystal- 

 lizable from soil extracts and to determine, if possible, the variations in these 

 In different types of soil are reported. 



It was found that salts deposited on the evaporation of the water extract 

 of soils are much more complicated in character than is indicated by a simple 

 statement of the ions existing in solution. There is a marked general simi- 

 larity iK'tween the salts .so obtained and those obtained by both natural and 

 artificial evaporation of sea water. It is considered probable that the complex 

 salts obtained from soil extracts may be present in the soils only in solution in 

 soil moisture and never in the solid phase. 



A bibliography is appended. 



The distribution in the soil of currents emitted by electric traction lines, 

 GiRoussE (Compt. Rend. Acad. .s:«. [ParLf], 170 {1920), No. U, pp. SJfl-843).— 

 A mathematical discussion is given of the distribution and intensity of elec- 

 trical currents leaking from electric traction lines into the neighboring soils. 

 Formulas are derived, based on the electrical resistance of the soil, the amper- 

 age and voltage of the electrical current, and other factors. 



The potential biochemical activity of the spores of soil bacteria, J. R. 

 Neixer (Soil Sci., 9 {1920), No. 5, pp. 329-340, fig. J).— Studies at the New 

 Jersey Experiment Stations are reported, in whicli laboratory tests were 

 conducted with infusions from the five successive layers of the upper B4 cm. 

 of gravelly loam and shale loam soils, which were heated to 85° C. for 10 

 minutes, and the carbon dioxid production, ammonia accumulation, and bac- 

 terial numbers were compared with a similar treatment with unheated in- 

 fusions. 



In the surface soil of the finer textured loam 5.8 per cent, and of the coarser 

 loam 8.7 per cent of the original bacterial count, survived a temperature of 85' 

 for 10 minutes. The relative numbers surviving in the subsoils were much 

 less, being 2.7 and 1.6 per cent, respectively. Very few fungus colonies and 

 no actinomycetes or chromogenic types were observed in the plates inoculated 

 with heated infusions. 



For a 7-day period the average ammonia accumulation resulting from inocu- 

 lating with heated infusions was 46.0 per cent of that with unheated infusions 

 obtained from gravelly loam and 39 per cent when infu.sions from shale loam 

 were used. For a 10-day period the carbon dioxid produced by inoculating with 

 heated infusions of Bcunllus subtilis was about the game whether the infusion 

 had been heated for 5, 10, or 15 minutes, and averaged 73.6 per cent of the 

 amount produced by unheated infusions. For a 7-day period the average 

 carbon dioxid production resulting from the use of heated infusions of shale 

 loam was 77 per cent of that obtained with unheated infusions. The corre- 

 sponding value for gravelly loam was 76.2 per cent. The accumulation of 

 ammonia and the production of carbon dioxid resulting from inoculating a 

 sterile soil with heatwl infusions correlated with each other in showing that 

 the bacterial spores of the soil are capable of energetic activity when supplied 

 with sxifficient food and moisture. 



Symbiotic nitrogen fixation as influenced by the nitrogen in the s<wl, 

 W. A. Albrecht {Soil Sci., 9 {1920), No. 5, pp. 275-327, figs. 7).— Following an 

 exten.sive review of the works of others bearing on the subject, studies con- 

 ducted at the University of Illinois are reported on the relation of symbiotic 

 nitrogen fixation to the nitrogen content of soils, particularly the total nitro- 

 gen as obtained by soil analysis. 



Variations in the mineral and organic nitrogen content of the .soil were 

 brought about by adding sodium nitrate, and by incorporating organic matter 



