:\\[ EXPERIMENT STATION RECORD. 



Rothamsted, on which there are plats manured with sodium nitrate, it is found that 

 the soil "t" these plats generally contains a lower proportion of the finest 'klay' 

 fraction than does the soil of adjoining plats which have been either unmanured or 



have received a ionium salts in place of sodium nitrate. This result was must 



manifest in the mangel field where cultivation is frequent, and was not apparent at 

 all in the grass field where the turf protects the soil from the washing action tit tin- 

 rain. 



•'The removal of the finest particles from the surface soil is attributed to defloc- 

 culation induced by the use of sodium nitrate, and followed by the washing of the 

 finest particles into the subsoil. This hypothesis is confirmed by chemical analyses 

 of the 'klays' separated in the mechanical analysis, by the examination of some of 

 the subsoils, which are found to be richer in fine particles beneath thesoils receiving 

 nitrate, and by the condition of the soils in the field, which show every evidence of 

 deflocculation." 



Soil fertility in the light of recent investigations, S. Bogdanov {Selsk. Khoz. 

 i Lyesov., ;ll (1903), Nov., pp. 249-284)- — The author reviews the work of Oyer 

 (E. S. R., 5, p. 1013) on acidity of root juices; of Prianishnikov, Kossovich, and 

 Shulov ( E. S. R., 13, pp. I':;."', 934; 14, pp. 343, 427) on the assimilation of the phos- 

 phoric acid of raw phosphates by different plants; of Schloesing and Paturel ( K.S. R., 

 I:;, p. L029; 14, pp. 127, 233, 341; 15, p. 760) on the phosphoric acid of soil solutions; 

 of Fesca " on the solubility of soil constituents in water; of Czapek and Kohn h on 

 root secretions; and others, in so faras these investigations relate to the alleged power 

 of plants to assimilate difficultly soluble soil constituents by means of acid secretion 

 of their roots. 



He reaches the conclusion that in the strict sense there are no root secretions 

 either acid or alkaline, but that plant roots in taking up the necessary constituents 

 exercise a selective influence on the soil solution which varies with different plants 

 and stages of growth and with the character of the soil. The plants undoubtedly 

 play apart in dissolving substances from the soil, but this consists mainly in selecting 

 the needed plant food from the soil solutions, thus helping the soil water to dissolve 

 new quantities of nutritive substances. The physiological residues of the salts util- 

 ized by the plants may play a part, dependent upon the needs of the plants for 

 nutritive substances and upon the chemical peculiarities of the soil. A part may 

 also he played by the carbon dioxid which is exhaled by the roots of different plants 

 in varying amounts. 



It is pointed out, however, that the physiological residues of the salts, as well as 

 the carbon dioxid exhaled by the roots, may be of importance only in the artificial 

 conditions found in most experiments, especially such as prevail in sand cultures. 

 In normal soils there are usually present plenty of substances which rapidly neutral- 

 ize the physiological residues, and, since carbon dioxid is formed in normal soils in 

 abundance at the expense of decomposing organic substances, the additional carbonic 

 acid exhaled by the roots can scarcely be of much consequence.— P. fireman. 



Investigation of some chemical and physical properties of the separate 

 products of the mechanical analysis of podzol and loess, D. P. Mazurexko 

 (Inaug. Diss., Munich; abs. in Zhur. OpwUn. Agron. [Jour. E.rj)t. Landw."], 5 (1904), 

 No. /, pp. 73-75). — The author employed the Fadyeyev-Williams method of mechan- 

 ical analysis and operated on a rather large scale in order to obtain each fraction in 

 sufficient quantity. The experiments were made with two strikingly different soils, 

 a loess from the basin of the Donetz River and a podzol from the farm of the Moscow 

 Agricultural Institute. 



« Jour. Landw., 1873, p. 459; Jahresber. Agr. Chem., 16-17, 1873-74, p. 126. 



& Jahresber. Wiss. Bot., 29(1896), p. 321; Landw. Vers. Stat., 52 (1899), pp. 315-326. 



