ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably 

 prepared and signed by themselves, are forwarded promptly to the editors. Each 

 of the scientific bureaus in Washington has a representative authorized to for- 

 ward such material to this journal and abstracts of official publications should 

 be transmitted through the representative of the bureau in which they originate. 

 The abstracts should conform in length and general style to those appearing in 

 this issue. 



AGRICULTURAL CHEMmTRY .—Selective adsorption by soils. E. 

 G. Parker. Journal of Agricultural Research 1: 179-188. 1913. 



Soils not onh^ have the power of adsorbing dissolved salts from solu- 

 tions but also of adsorbing one ion at a greater rate than another. 



The presence of bases of the soil (Ca, Mg, etc.) in solution after 

 shaking certain salt solutions with or percolating them through a soil 

 is probably not due to a direct chemical reaction of the salt in solution 

 ^vith the silicates of the soil, but to a reaction of free acid, resulting 

 from a selective adsorption of the cation, with the mineral components 

 of the soil. The rate of adsorption of chlorin ions from a solution of 

 potassium chlorid by soils is much less than of potassium ions. The 

 selective adsorption of potassium from a potassium-chlorid solution 

 by a soil increases in amount with the concentration up to a certain 

 point and then remains practically constant. In general, the smaller 

 the soil particles the greater the selective adsorption of potassium from 

 a potassium-chlorid solution. The presence of sodium nitrate decreases 

 the adsorption of potassium from a solution of potassium chlorid by a 

 soil up to a concentration of about 37.5 grams of potassium chlorid per 

 liter and then increases it. The presence of monobasic calcium phos- 

 phate does not change appreciably the adsorption of potassium from a 

 potassium-chlorid solution. 



Finally, if a mineral fertilizer be applied to a soil and exposed to the 

 rain and thus dissolved and carried through the soil in solution, these 

 substances will be adsorbed (an entirely physical phenomenon) either 

 as a whole or selectively from the solution by the vast surface of the 

 soil particles and will be held there by this same physical force until 

 the plant or subsequent leaching removes it. 



143 



