22 



THE PHYSICAL ACTION OF LIME ON CLAY SOILS 



With the soils treated for 45 days, liming seemed to decrease the 

 adsorptive power when applied in excessive amounts. The same applies 

 to calcium hydrate and gypsum for the 225 day treatments. On the 

 other hand, limestone and precipitated carbonate increased the adsorp- 

 tive power slightly. It may be that the analogy of internal surface does 

 not apply to organic matter, and that the influence of salts on the 

 adsorptive power is primarily chemical rather than physical. 



Adsorption experiments were conducted with diamine sky blue and 

 with diamine violet, both of which are specific for hydrous aluminum 

 oxide. Unfortunately neither is stab'le in the presence of very much elec- 

 trolyte, and experiments could be conducted with soils which had been 

 limed not to exceed a ton and a half per acre. The tests failed to show 

 any differences in adsorptive power. In other words, limes do not 

 precipitate hydrous aluminum oxide when added in the equivalent of a 

 ton and a half per acre. The writer has found eosin to be much better 

 than either of the above dyes for the study of the adsorptive power of 

 aluminum. Its adsorptive equilibrium is not influenced by salts present 

 in solution in the equivalent of 10 tons per acre. 



ADSORPTION OF EOSIN BY SOILS TREATED FOR 45 DAYS 



ADSORPTION OF EOSIN BY SOILS TREATED FOR 225 DAYS 



It seems from the above data that all limes precipitate aluminum to 

 some degree. Probably gypsum has a stronger action in this respect 

 than any of the others. 



Taking the adsorption data as a whole, it appears that the primary 

 effect of liming is the precipitation of the silicic acid, as indicated by the 

 methylene blue tests. The influence of lime is noticeable, even when 

 added in very small amounts. Indirectly, we also get a precipitation 

 of the aluminum, and perhaps the organic matter. Any statement as to 

 the effect on the colloidal iron will have to be deferred until a suitable 

 dye is obtained. 



