116 Phenomenon of Ahsorptioti in its Relation to Soils 



E. Biedermann^ made a further comparison with 23 soils from various 

 parts of Saxony and also obtained results in fair agreement with the 

 assumption — exceptions were noted chiefly where the absorbed ammonia 

 was replaced almost entirely by magnesium, the soils being then some- 

 what infertile. 0. Kellner^ varied the procedure somewhat, and deter- 

 mined the amount of available bases by boiling the soil with successive 

 quantities of ammonium chloride solution. He states that the amounts 

 of potassium and calcium thus removed are precisely equal to the 

 quantities obtainable by plants. This he showed by the following 

 experiment. 



Twenty-two pea plants were grown for six weeks in 369-15 gms. of 

 soil placed in a funnel plugged with asbestos and watered with a diluted 

 solution of ammonium nitrate, 1 gm. of which was supplied during the 

 whole period. The soil was analysed for available plant food by the 

 above method. The amount of food material in the plants was also 

 determined. The results are as follows: 



This rather remarkable statement does not seem to have been since 

 confirmed in spite of its obvious importance. 



Recently E. Ramann has introduced a further modification : a 5 % 

 ammonium nitrate solution is allowed to percolate through the soil and 

 the displaced potassium or other plant food is determined. He speaks 

 of this as a "Base exchange" {Basenaustausch)^. A similar "Base 

 exchange" was obtained by 0. Kiillenberg^ with calcium, magnesium 

 and sodium salts. Using these in various concentrations the final 

 equilibrium resembles those already attained by Peters with potassium 

 and Henneberg and Stohmann with ammonium salts. 



1 Landiv. Ver.mrhs-Skd. 1869, 11, 1; 1872, 15, 21. 



2 Ibid. 1886, 33, 349 and 359. 



3 J. A. Hanle.y, Nature, 1914, 93, 598. International Commission on the Chemical 

 Analysis of Soils. 



* Jahresb. Aijric. Chemie, 1865, 8, 15. 



