SOILS FEBTILIZERS. 1 lM 



barley grown in sterilized -and. with various combinations of soluble and insoluble 

 phosphates and with nitrogen in form of sodium nitrate, ammonium nitrate, and 

 ammonium sulphate. Ingenious apparatus used to secure and maintain perfecl 

 sterilization, and thus to prevent nitrification, which the author considers the inde- 

 terminate factor in the investigations of Prianishnikov and Shulov, is described in 

 detail. 



The barley was sown July 25 and normally developed plants were harvested Sep- 

 tember 10. The author concludes from the results obtained thai under the sterile 

 conditions maintained the plant utilized equally well the nitrogen from nitrate- and 

 from ammonium salts. The form of combination of nitrogen, however, exerted ;l 

 decided indirect influence on the growth of the plant and the assimilation of plant 

 food by modifying the culture medium. 



Plants receiving only nitrogen in for t' nitrates took up relatively more acids 



than bases, thus pausing an alkalinity of the nutritive medium, which may have 

 exerted an injurious influence on the growth of the plant and influenced the ability 

 of its roots to dissolve the needed plant f 1. When only nitrogen in form of ammo- 

 nium salts was present, the plant took up relatively more of the bases than of the 

 acids, and thus brought about an acid condition of the medium which was likewise 

 injurious to plant growth, unless sufficient neutralizing material was [.resent in the 

 soil. This acid condition, however, facilitates the solution of other plant food con- 

 stituents, such as the- phosphoric acid in insoluble phosphates. 



When nitrogen in form of both ammonium salt- and nitrates was present, the 

 plant utilized nitrogen equally from both source- w ithoul sensibly affecting the reac- 

 tion of the medium. The conditions were in this case, therefore, most favorable for 

 normal development, p. fireman. 



On different degrees of availability of plant nutrients, 0. Loew and K. A.S0 

 I /.'/</. Col. Agr., Tokyo Im/>. Univ., <; \ inn:,), No. 4, />/>. 835-346) .—The authors dis- 

 cuss the varying chemical availability of lime and magnesia and of phosphoric acid 

 under different conditions, stating that Loew's hypothesis as to the most favorable 

 ratio of lime to magnesia is predicated upon an equal state of availability of the two 

 bases. 



"This ratio changes, however, with the difference in availability, since of the 

 more available form also more of the base will enter into the plant and thus the ratio 

 offered to the roots and that which enters into the plant body will differ. Magnesia 

 in the form of burnt magnesia is more available than in the form of pulverized mag- 

 nesite and in the form of magnesium sulphate still more available. The amounts in 

 which the easily available forms of lime or magnesia can produce the same resull as 

 E00 parts of the natural carbonates in the finest powder it is proposed to call the 

 agronomical equivalent. This [factor] changes with the nature of the soils, and the 

 partial transformation of the applied compounds into other forms in the soil. 



"The action of lime and magnesia in physiological respect has to he distinguished 

 from the actions these bases exert on the soil. 



"The [reason] why lime in the form of gypsum acts differently from lime in the 

 form of carbonate or slaked lime is the low degree of availability, since dilute acids 

 do not increase the solubility. Even heavy doses of gypsum in the soil do not aug- 

 nient essentially the lime content of the leaves, and an excess of gypsum i- not so 

 injurious as an excess of carbonate. 



"The decrease in harvest by liming certain soils is not always due to a diminution 

 of the availability of phosphoric acid, but may in many cases be due to the produc- 

 tion of a very unfavorable ratio of lime to magnesia. The magnesia content of soils 

 has always to be taken in account when [lime and phosphatic manures are applied]." 



The determination of the productiveness and plant food requirements of 

 soils, .1. Kom,, i Landw. Vers. Stat., 61 [1905), No. 5-6, pp. 371-396).— A discussion 

 of this subject based u| .on a critical review of Literature relating to it, the subject 



