7fiO KXPERTMENT STATION RECORD. 



Tlii'v tcMili lliat a Irrlilc licM is inexliaustil>lc in rcjiard to the fixi'd .su])staiu:cs 

 wliicli i>laiils ciMitaiii, and coiisciiiicntly can never become deficient." 



In the autlior'sDiiiniun a^roiKniiists imbued with sucli prejudices could not attach 

 anv real importance to chemical analysis of the soil. It should l)e stated, moreover, 

 that the metlio(lsof chemical analysis were very imperfect at that time. In fact, the 

 car!ii-r methods of clu-mica! analysis of soil were so unreliable and therefore came 

 into sucii disrepute that many eminent chemists, includin»j Fresenius, jNIiintz, Risler, 

 Colond)-Pradel, Schloesin<r, Berthelot and Andre, Petermann, (iranileau, and Wolff, 

 devoted a {jreat ileal of attention to studies having as their object the im])rovement 

 of tiu'se methods. .\s a result of this activity, however, chemictal methods were 

 made so comiilicati'd and tedious as to become impracticable, wliile at the same time 

 thev did not show in a precise manner the influence of the soil on the growth of 

 plants. 



Chemical analysis is capable of showing with great accuracy, and with close agree- 

 ment in the hands of indep^;ndent analysts, the percentage composition of soils, ])ut 

 can not ])e relied vipon to show the form of combination or the availaliilitv of the 

 constituents, nor does it furnish a relia])le basis upon which to estimate the amounts 

 of plant food whicli may be rendered available during the growth of a croji by the 

 physical, chemical, and biological agencies constantly at work in the soil. 



Even with the most complete information furnished by a complete chemical analy- 

 sis of soil, no one can deduce from it, with any certainty, the results which will be 

 obtained l)y analysis of the soil by the plant. The chemist can, however, instruct us 

 upon the nature and the total quantity of elements necessary, useful, indifferent, or 

 injui-ious to vegetation whicrh the soil contains; and such precise knowledge of the 

 cliemical composition of the soil, as well as of its mineralogical, geological, and 

 Iihysical characteristics, is essential to the proper interpretation of the results of 

 ]ihysiological analysis. 



The water-soluble potash of the soil and its utilization by plants, T. 

 ScHLOESiNG, Jr. {('umpt. Rend. Acad. Sri. Paris, 137 [1903), No. 26, pp. 1206-1209; 

 abs. in Rev. Sci. [Paris'], 5. ser., 1 {1904), No. 2, p. 55). — In earlier experiments plants 

 grown in artificial soils of i)ure (juartz were able to derive their jiotash from solu- 

 tions applied to the soil which contained only from 1.8 mg. to 7.5 mg. of potash per 

 liter (E. S. R., 12, p. 36). 



Further experiments were made by the same method followed in similar studies 

 on water-soluble phosphoric acid in the soil (E. S. R., 14, p. 341), to determine 

 whether j^lants are able to derive their potash from such dilute solutions as occur in 

 natural soils. Samples of 4 different soils used in 2 series of experiments, in one of 

 which plants were grown and in the other the soil was kept bare, were exhausted 

 by continuous extraction with water and the potash so removed from the cropped 

 and uncropped soils determined. The jiroportion of potash so removed was in all 

 cases smaller on the cropped soil than on the uncropped soil, the difference between 

 the 2 varying from 65 to 123 mg. per kilogram of drj^ soil and approximating quite 

 closely in every case the amounts of potasli found by chemical analysis in the crop 

 grown. 



On the influence of the relative proportions of lime and magnesia in soils 

 on the yield, O. Lokw {Client. Ztij., 27 (1903), No. 100, pp. 1225, i^-- JO').— Referring 

 to a recent article by Gossel {E. S. R., 15, p. 564) containing conclusions not in accord 

 with Loew's theory of a necessary relation between lime and magnesia in soils, the 

 author points out that, while the details of Gossel's experiments are not reported, the 

 disagreement of his results with those of Loew and his associates may be explained 

 by the fact that Gossel used secondary potassium phosphate in his experiments, 

 while in the other experiments primary ])otassium phosphate was used. It has been 

 shown that the secondary phosphate greatly reduces the injurious effect of an excess 

 of magnesium salts in water cultures. 



