il»101 SOILS — FF.KT1UZKRS. 513 



soil, to the utilization <>f the salts by organisms, and to the formation <>f less 

 soluble compounds. 



The concentration <»f the soil solution in the soil was variable) differing 

 somewhat in several soils with the seasons, rainfall, at different depths, and 

 with plant growth. It is thoughl probable that "variations in the concentra- 

 tion of the soil solution in some instances at least, have not been sufficiently 

 considered in biological studies where conclusions have been drawn based upon 

 the results obtained from studies of the water extracts of soils. Moreover, it 

 does not seem possible to determine the fertilizer needs of soils by obtaining 

 water extracts and growing plants therein. The seasonable variation in the 

 soluble salt content of soils doubtless plays an important role in the results 

 obtained from the use of fertilizers." 



Effect of carbon disulphid and toluol upon nitrogen-fixing and nitrifying 

 organisms, P. L. <!ai.\kv {Jour. A</i. Research [V. S.], 15 {1918), No. It, pp 

 601-614).- Continuing previous investigations at the Kansas Experiment sta- 

 tion (B. S. K., 30, p. 717), and iisin^ similar methods, the author studied more 

 specifically the effect of carbon disulphid and toluol on the nitrogen-fixing and 

 nitrifying organisms of soils under varying conditions of moisture. 



The conclusions reached were that " carbon disulphid and toluol when applied 

 to soils in sufficient quantities will destroy Azotobacter group of organisms and 

 check the accumulation of nitrate nitrogen, and possibly will destroy the nitrify- 

 ing organisms. The quantities necessary to produce such effects vary quite 

 widely, depending among other tilings upon the quantity of moisture present 

 Apparently if the quantity of carbon disulphid or toluol is sufficient to have any 

 effect upon Azotobacter they are usually completely destroyed. On the other 

 hand, there is a greal difference in die quantity necessary to destroy nitrifying 

 organisms and that necessary to check their activity. There are nitrogen-fixing 

 organisms other than Azotobacter present In soils which are not destroyed with 

 10 cc. of carbon disulphid or toluol [to ."id gm. of soil] even when the moisture 

 content of the soil is high. Following treatment with carbon disulphid and 

 toluol there is no appreciable accumulation of ammonia unless nitrification lias 

 been checked. There is no evidence in these experiments to show that treatment 

 with antiseptics stimulates the nitrifying organisms, and there is little evidence 

 to indicate a stimulative effect upon thu ammonifying or nitrogen-fixing or- 

 ganisms." 



Influence of higher plants on bacterial activities in soils, T. L. I.ton 

 (Jour. Amer. 8oc. Agron., 10 {1918), X». <>, pp. 313-322).— In this paper, pi. 

 sented as the presidential address before tiie 1918 meeting of the American 

 Society of Agronomy (B. S. K., 40, p. 299), the author briefly reviews experi- 

 mental work dealing with the immediate effect of growing plants on certain 



bacterial processes in the soil. Particular reference is made to the nitrogen 

 transformations. The necessity is pointed OUi for improved methods in study- 

 ing the chemical and biological changes occurring In the soil for a proper solu- 

 tion of the problem. 



Bacteria of frozen soils in Quebec, I, II. J. VAITOEBLECK {Proc. ami Trans. 

 Boy. Soft Canada, 3. ucr., 11 {1917), Sect. IV, pp. tS-37, i>ls. .}, jia.s. ,{,- flj 

 (1918), Sect. IV-V, pp. 1-21, /i<is. 6). — Investigations begun during the winter 

 of 1914-15 are described in which observations were made upon the number 

 of bacteria occurring in a cultivated soil, under a sod, in soils from various 

 localities, in soil from a plat covered with snow ami in which a gradual hori- 

 zontal penetration of frost had taken place, and in soil from an exjiosed hilltop. 

 The weather conditions during the winter of 1914 15 and 1915-16 are said to 

 have been rather unfavorable for these observations, while the winter of 1916-17 



