SOILS FERTILIZERS. 119 



"(2) Nitrification is nil or very slislit in saturated soils. 



"(3) Nitrification in some soils proceeds as fast as anunonification. convertin}; 

 the annnonia to nitrate as fast as it is rendered available by the anniionifyinK 

 organisms. 



"(4) Nitrification in extract of soil is. in some instances, very slight as c-om- 

 pared with nitrification in tlie soil itself. 



"(5) Nitrification in soils increases in intensity with the amount of inoculum 

 used. 



"(6) Some nitrifying soils do not nitrify when iilaced in solutions even 

 though a very large inoculum is used. 



"(7) Nitrifying organisms from sewer beds nitrified [letter in solutions tlian 

 in soils. 



"(S) Tests in solutions are not adequate to indicate the nitrifying vigor of 

 a soil." 



Studies in soil bacteriology, I. Nitrification in soils and in solutions. 

 F. L. Stevens, W. A. Withers, et al. (North Carolina Sta. Rpf. lilOht. />/>. 

 40-63). — Noted above from another source. 



Investigations on the process of nitrogen assimilation in its relation to 

 soil climate, T. Ueuy (Ccnthl. Bald. \clc.]. 2. Abt., 22 (190!)), No. 18-23, 

 pp. 661-651, ph. 11, fig. 1; ahs. in Chcm. Zcnthl., 1909, I, No. 13, p. 1109; Jour. 

 Chcm. Soe. [London], 96 {1909), No. 5.58, II, p. 3//0).— Delbruck's use of "soil 

 climate" to mean the sum of life conditions in nutrient media (soils) is fol- 

 lowed in this article, which deals not only with the relation between soil climate 

 and the nitrogen fixing power of soils, but also with the best methods of measur- 

 ing the latter. Numerous investigations, some of them going back as far as 1902, 

 in which the author's well known methods were employed, are quite fully re- 

 viewed. These investigations, which have been in large part ali-eady noted, 

 dealt mainly with the effect on bacterial activity of cultivation and other 

 forms of soil manipulation, fertilizers and other nutrient substances, acidity, 

 basicity, moisture, nitrogen content, and various other conditions in soils and 

 media. 



The experiments show in general that both in small laboratory experiments 

 and in experiments with larger amounts of soil there is a considerable fixation 

 of nitrogen and that this nitrogen is a useful source of supply of this con- 

 stituent to higher plants, being not less readily available than the best forms of 

 organic nitrogenous fertilizers. 



The possibility of working out practical means of increasing and controlling 

 the fixation of nitrogen in soils is discussed. In general the conditions which 

 are to be sought in practice are those which increase the stock of humus in the 

 soil and at the same time promote its decomposition to yield readily assimilable 

 sources of energy to the nitrogen fixing organisms. 



On nitrification in soils in place, Pouget and Guiraud {Compt. Rend. 

 Acad. Set. [Pari.'i], 1J,8 (1909), No. 11, pp. 725-727; ahs. in Rev. 8ci. [Paris], 

 1,7 (1909), I, No. 13, p. J,ll; Chem. ZentbL, 1909, I, No. 19, p. 1601; Chern. Abs., 

 3 (1909), No. 13, pp. 1166, 1167). — Investigations are reported which show that 

 during the winter on the Algerian seacoast nitrification in place is not retarded 

 excejtt when the soil is water-logged by excessive rain, l>ut that when it is thus 

 interrupted it stai'ts again with difficulty and does not become active until about 

 the end of May, nearly a month after the close of the rainy season. During 

 summer nitrification is active in a compact soil, but is often accompanied by 

 denitrification. The decrease of the nitric nitrogen content of the soil during 

 this season can not be attributed to drainage, because the rainfall is small and 

 the rapid evaporation from tlie soil would tend to concentrate the nitrates in 



