SOILS FERTTLTZEKS. 2 1 5 



Investigations on the insoluble alkali compounds existing in the humus 

 substances of the soil and their role in plant physiology and agriculture, 

 M. Bekthelot (Ann Chim. et. I'hys., S. set:, S {190G), Muij. iii>. 5-D ; ahs. in 

 Chrm. Ztt/., 30 (1906), .Yo. ;>,s', licpert. Xo. 22, p. 252).— Sec E. S. K.. 17. ]>. r,44. 



The removal of salts from soils in Egypt, R. Aladjem (Jour. .1//;. I'ntt., 

 n. Kcr., 12 (1906), So. 33, pp. 21.'), 216). — The uietiiods of flooding; and draiiiai^c 

 eini)loyed for this purpose are described. 



A saline soil of the lower valley of the Po, V. Peglion (.Itti R. Accatl. 

 Ecoii. Agr. Firenzc, .'>. scr., 3 (19(i6). So. I. pp. .19-6 j). — The proportion 

 .and the coni])ositiou of tlu> soluble salt (alkali) in tbc soil are rejiorted. 



On the absor^Dtion of alkaline carbonates by the mineral constituents of 

 soils, J. DUiMONT and L. Maquenne (Compt. Rend. Acad. Sci. [Paris], l'i2 

 (1906), So. 6, pp. 3J,.5-3.',~ ; ah.s. in Rcr. fici. [Paris], ■',. .spr., 5 (1906), So. 7, p. 

 210; Jour. Chcin. 8oc. [London]. 90 (1906), So. 522, II, p. 2//9).— The extent of 

 absorption due to chemical changes w.as determined by nieasurinj;- the amount of 

 carbon dioxid evolved when a solutiou of potassium carbonate was added to 

 moistened clay, fine sand, kaolin, silica, iron hydrate, and alumina, and allowed 

 to stand for some time. 



The results indicate that the sandy constituents of soils do not exert any 

 decomposing action on alkaline carbonates ; kaoliri acts very feebly in this 

 respect ; silicic acid even when dried decomposes potassium carbonate in the 

 cold, but to a less extent than other colloidal substances ; hydrates of iron and 

 aluminum act very energetically, and tlie action of alumina particularly is in 

 all respects comparable with that of clay. It appears that the absorbent prop- 

 erty of clay exceeds that of its constituents talcen individually or collectively. 



In a note on this article Maquenne maintains that the absorbent property of 

 clay is due to and is a necessary consequence of its chemical com[)osition. The 

 position of the OH groups in clay is such that the latter can form with both 

 bases and acids, compounds which are probably dissociable by water. 



On the influence of bacteria on the metamorphosis of nitric acid in soils, 

 J. Stoklasa and E. Vitek (Ztsclir. Liuulir. Versuchsir. (isfcrr., 9 (1906), So. 2, 

 pp. Jf9-10o). — The authors' investigations with a great variety of organisms in 

 different media lead to the conclusion that nitrous acid is always the inter- 

 mediate product in the reduction of nitrates liy these organisms. It was found 

 that carbon dioxid and hydrogen are jiroduced from the carl)ohydrates or organic 

 acids of the culture media and that the nascent hydrogen conil)inos with the 

 oxygen of the nitrates to form water and thus reduces the latter to nitrites. 

 A hypothetical scheme for such breaking down of glucose with production of 

 hydrogen is given. In the same way denitrifying organisms reduce chlorates 

 to chlorids, arsenates to arsenites, ferricyanids to ferrocyanids. 



Certain of the most widely distributed carbohydrates in soils and manures, 

 as for example, xylose and arabinose, are not specially good nutrients for deni- 

 trification bacteria, but favor slow amnionisation of nitric and nitrous a<'ids. 

 It is true, however, that the typical denitrifying organism Bacillus Jiartlcbi in 

 a medium containing arabinose was able to assimilate 33.()2 per cent of the 

 nitrogen of nitrate and convert it into protein substances. The soil also fre- 

 quently contains carltohydrates. such as the hexoses, and organic acids, which 

 favor denitrification. Nevertheless, denitrification as a rule plays only a 

 secondary role to nitrification and ammonisation in soils. 



The authors' studies of a number of beet soils showed that the ammonisation 

 bacteria predominated in them, Clostridium gelatinosuni being especially preva- 

 lent, but associated with other organisms which play an inii)ortant part in con- 



