SOILS — FERTILIZERS. 27 



advisable to take a temperature as little above the death point of the active 

 ciliates as is absolutely necessary to insiu-e the killing of these organisms. 

 Probably a temperature of 58 to G0° would be suitable for this purpose." 



The action of antiseptics in increasing the growth of crops in soil, E. J. 

 ItussixL and W. Btjddin {Jour. Hoc. i'hcm. Indus., 32 (1D13), No. 24, PP- IISG- 

 1142 figs. 5; ahs. in Chem. Zentbl., 1014, I, No. 8, pp. 806, 807; Rothamsted 

 Expt. 8ta., Harpenden Ann. Rpt. WIS, pp. 17, 18). — In continuation and exten- 

 sion of previous work (R S. R., 28, p. 538; 29, p. 122; 30, p. 219) the authors 

 studied the relative effectiveness of individual volatile and nonvolatile anti- 

 septics for partial sterilization of soils. 



The action of toluene is said to be typical of that of the whole class of vola- 

 tile antiseptics studied as it causes first a decrease and then an increase and 

 also a change in type iu the micro-organic population of the soil, the susi>ension 

 of nitrification, a marked increase in ammonia in'oduction, and the liberation 

 of very small amounts of ammonia. The volatile antiseptics studied are classed 

 in order of their effectiveness as follows: Toluene, carbon bisulphid, benzene, 

 cyclohexane, chloroform, ether, hexane, and methyl and ethyl alcohols. 



"The nonvolatile antiseptics present a more complex case because they per- 

 sist in the soil and modify the development of the bacterial flora." Cresol is 

 said to be typical of this class and its later effects differ from those of the 

 volatile antiseptics in that the bacterial numbers are unusually increased, the 

 flora is less mixed and very simple, and the high numbers of oi'ganisms do not 

 persist but decrease rapidly to the numbers in untreated soil. " Simultaneously 

 there is an increase in the amount of ammonia formed in the soil, but nothing 

 corresponding to the increase in bacterial numbers." Fhenol resembles cresol 

 in its action but the rise in bacterial numbers is more marked and there is an 

 even smaller production of ammonia. Hydroquinone behaves somewhat like 

 phenol, the quiuone is similar but is less potent. Formaldehyde is normal iu 

 its initial behaviour but subsequently there is a marked rise in the amount of 

 ammonia produced but no increase in the bacterial numbers above what occur 

 in the untreated soil. 



" Pyridin is the nearest approach to a nitrogenous antiseptic. All the non- 

 volatile antiseptics in higher doses bring about a dei)ression in the amount of 

 nitrate revealed by aualy.sis." 



As regards their beneficial effect on plants grown in ix)t experiments with 

 soils containing disease organisms the antiseptics tested are classed as follows: 

 Most effective, formaldehyde and pyridin ; medium, cresol, phenol, calcium sul- 

 phid, carbon bisulphid, toluene, benzene, and petrol ; least effective, higher 

 homologues of benzene and naphthalene and certain of its derivatives. " None 

 of these antiseptics is as good as steam, either in increasing the amount of 

 ammonia in the soil, in killing insect and fungoid pests, or in inducing a good 

 fibrous root development." 



It is concluded that antiseptics may be used with advantage in practice where 

 the crop yield is limited by the supply of nitrogenous plant food, and whare 

 disease organisms and other detrimental forms are present and the micro- 

 organic population of the soil has lost much of its effectiveness in producing 

 ammonia from the nitrogen compounds therein. 



A list of previous articles on the sub.iect is given. 



Pertilizers and soil organisms, C. Lumia (Mem. R. Accad. Lincei, CI. Sci. 

 Fis., Mat. c. Nat, 5. scr., 9 {WIS), No. 12, pp. 457-471).— The results of the 

 author's investigations and observations confirm results obtained in previous 

 work (E. S. R., 14, p. 647). He concludes that the mineral constituents of 

 fertilizers and also carbohydrates exert a direct and favorable action on the 

 micro-organisms of the soil, and may be in part utilized directly by some of 



